Oven Roasted Tomato Ketchup

Homemade Ketchup

Homemade Ketchup – Step-by-step instructions on how to make your own ketchup that you and your kids will love.

There are many times when my aspirations heavily outweigh my inspiration. It is times like these that I end up with 25 lbs of tomatoes that I wanted to wish away.  They did not, however, turn themselves into the ketchup they were purchased to become nor did they disappear. They continued to ripen and I did not want to throw money away.

I made the ketchup using a new technique that I figured out because the recipes I followed last year were, frankly, a pain in the ass. Taste wise they were fine but it was really annoying to try and fit 10 lbs of tomatoes into the biggest pot I had, and still have it fall short. The recipes said to put the tomatoes in raw and cook them down and then puree them usually using a food mill. Well, I bought a food mill and I hate it. I have a food processor so no one can convince me that a food mill is better, because I am lazy. Sure, maybe you end up with a nicer texture but I don’t feel the need to add an extra hour cranking the handle on a food mill to the already long process of making ketchup. Admittedly, I do not own a really good food mill because I couldn’t really justify spending $75 on a new kitchen tool. The one I bought was $20 and I got it at Zehrs (grocery store). If anyone wants it, let me know.

Last year I made Slow-Cooker Ketchup but I prefer the texture you get when you strain the tomato puree through a fine mesh sieve. I also made Classic Tomato Ketchup but there was no way I could fit the 12 lbs of tomatoes in my big cast iron enamelled pot so I had to add them in stages. Supreme pain in the ass. This year, I still wanted the homemade ketchup but I needed to take some of the fussiness out of the method.

If you are like me and don’t have a pot large enough for 10 lbs of tomatoes, you likely have a pan big enough for a turkey. I mounded the tomatoes, chopped onion and pepper in my big stainless steel turkey roasting pan and roasted the lot for about an hour. I didn’t have to tend the pot by stirring it and keep adding the tomatoes that didn’t fit as the tomatoes cooked down. I didn’t worry about some tomatoes scorching on the bottom of the pot, or the juice boiling over. I just poked at the tomatoes with a wooden spatula after they had been cooking for a half hour. Once they were fully soft and pulpy I took them out and started to puree it all in my food processor.


Tomatoes to be roasted

Cut the tomatoes in half, chop the onion and pepper and put it all in a large roasting pan [Before Roasting]

Roasted tomatoes

[After Roasting] Tomatoes cooked down and pulpy after an hour in the oven.

Spices in a paper towel

Spices strained using a single ply of paper towel.

While the tomatoes roasted I put all spices directly in the vinegar, brought it to a simmer, put the lid on and turned the heat off. I let the spices steep for  the whole time the tomatoes roasted, except for the cinnamon. I took that out after about a half hour because it just got too strong in the first batch where I left it the whole time. I was out of cheesecloth (I totally forgot to buy some) so I strained the vinegar through one ply of paper towel. I separated the plys because I didn’t want the paper towel to absorb too much vinegar. I also moistened the paper towel so it sat better in my little sieve.

The pureeing and straining process is a little time-consuming. With the size of my sieve and food processor, I have to puree all the tomatoes in 4 batches. Not really hard work, just a little fussy. The best way I have found to push the puree through the sieve is to use a strong whisk and push the pulp through the sieve. By stirring the puree with the whisk you can push the puree through and scrape the bottom of the sieve at the same time.

Here are my final tips for you if you are jumping on the homemade ketchup bandwagon: wear black and long sleeves. The ketchup splatters a lot and if you are fool enough to wear a tank top like I was, a molten hot ketchup splatter will likely find your bare skin. I still have the mark on my shoulder. I’m just happy that Timothy wasn’t in the room to hear my colourful choice of words when I got my ketchup scald.

Oven Roasted Tomato Ketchup

Oven Roasted Tomato Ketchup recipe that includes several techniques to simplify the process.

1 hrPrep Time

2 hr, 30 Cook Time

3 hr, 30 Total Time

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  • 10 lbs plum tomatoes (such as San Marzano)
  • 1 medium onion, chopped (3/4 cup)
  • 1 red bell pepper, chopped (3/4 cup)
  • 1 3/4 cup cider vinegar
  • 2 tbsp mustard seeds
  • 1 tsp whole cloves
  • 1 tsp celery seeds
  • 1 tsp whole allspice
  • 1 tsp whole peppercorns
  • 1 cinnamon stick
  • 1 1/2 tbsp salt
  • 1 1/4 cup lightly packed dark brown sugar


  1. Preheat the oven to 400 degrees F.
  2. Wash and cut all the tomatoes in half and place them in a large roasting pan.
  3. Chop the onion and bell pepper and mix them in with the tomatoes.
  4. Place the roasting pan in the oven and roast for an hour. Half way through cooking, stir the tomatoes around so that the tomatoes on top don't end up burnt.
  5. When the tomatoes go into the oven, put the cider vinegar in a small pot with all the spices. You will strain them out later. After a half an hour, remove the cinnamon stick or it becomes overpowering.
  6. When the tomatoes are soft and pulpy, take them out of the oven and puree them in batches in a food processor.
  7. Separate a piece of paper towel into its two individual plys. Lightly moisten one ply of paper towel and place it over a small fine mesh sieve. Pour the vinegar over the paper towel to strain out the spices. Discard the spices and paper towel. Set the spiced vinegar aside.
  8. Put the puree in a fine mesh sieve set over a very large heat proof bowl, also in batches, and push it through using a strong whisk, using a stirring motion.The whisk will push the puree through the sieve while it scrapes the bottom of the sieve allowing you to get the pulp through faster. Discard the seeds and skin left behind in the sieve. Scrape the pulp stuck to the underside of the sieve into the bowl.
  9. When the tomatoes are all strained through the sieve, pour the pulp into a large heavy bottomed pot. I use a 5 quart cast iron enamelled pot.
  10. Pour the spiced vinegar into the pot with the tomatoes. Stir in the brown sugar and salt as well.
  11. Bring the mixture to a boil over a medium high heat.
  12. While that starts to boil, bring a canning pot full of water, with a rack on the bottom, to the boil.
  13. Wash 6 half pint (250 ml) jars and new lids. Put the clean jars in the canning pot to sterilize. Boil them for 10 minutes and then turn off the heat to keep the jars hot and ready for the ketchup.
  14. Keep stirring the ketchup often to prevent scorching on the bottom.
  15. When the ketchup is less watery (after about a half hour) and is starting to splatter, place a spatter guard on top of the pot or prepare to clean up a lot of ketchup splatters from your stove, floor and counter. Also, turn the heat down to medium.
  16. Continue to boil the ketchup over a medium heat, stirring often as it cooks down until it is very thick.
  17. About ten minutes before the ketchup is done, put the lids of canning jars in small pot with water and heat it gently on the stove for 5 minutes. Put the lid on it to prevent ketchup splatters from getting in the pot. Once the water is hot, turn the heat off and let the lids sit in the hot water.
  18. To test to see if the ketchup is thick enough, take a spoonful and put it on a plate. If it stays in a mound and hardly any liquid spreads out on the plate then it is done. If a watery pool forms around the ketchup then keep boiling it down. You may need to boil the ketchup for upwards of an hour and a half to get the consistency of a nice thick ketchup.
  19. When the ketchup is the consistency you want, take the jars out of the hot water and place them on a heat proof surface, such as a large cutting board. Fill the jars with the ketchup, leaving 1/2 inch head space.
  20. Wipe the rims of the jars and place the hot lids on and rings. Tighten the rings (but not too tight) and place the jars in the boiling water of the canning pot and boil the jars for 15 minutes. Ensure that the water is boiling the entire time.
  21. When the time is up, remove the jars from the water and place on a rack or board. Leave the jars for 24 hours and if they seal then they can be stored in a cool dry place. If they do not seal then refrigerate them and use within a couple of weeks.
Cuisine: Preserving | Recipe Type: Condiment

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  1. Markus Mueller says

    This ketchup looks awesome!. I'm a big fan of making my own pesto, ketchup, flavored vinegar's.... any kind of condiment really. I'll need to make room in the fridge for a bottle or two of this!
  2. diversivore says

    I too have a habit of buying a LOT of produce with good intentions. In my case, I usually realize that I might have a great plan, but I haven't left myself enough time to actually act on those plans. I've already driven myself mildly crazy this year with 30 lbs of apricots, and I'm currently trying to figure out when exactly I'm going to finish turning the pounds and pounds of apples in my fridge into sauce and jelly. I like the approach you went with here, though I personally like my food mill, even if it is a cheapo one. I vowed never to make pasta sauce again until I picked one up on the cheap. As for the roasting aspect, your turkey pan approach is a GREAT one. Last summer I discovered my own new technique, and I'm totally hooked on it: the barbecue. I now roast tomatoes (or peppers) on the grill outside, then bring them in, nice and charred, to run them through the mill. Lastly - I love the spice blend you've used here! It sounds like a really great combination. Great read, great recipe - great job!
  3. Isabelle @ Crumb says

    I made the same mistake earlier this year when I picked up an entire flat of strawberries on a whim... I ended up spending the next two days making strawberry jam and strawberry shrub and strawberry liqueur and frozen strawberry puree, and by the end I was pretty much okay with not looking at another strawberry for the rest of the summer. Ugh. Never again. I love this big-batch approach to making ketchup. So much easier than hovering over a giant pot of simmering tomatoes and stirring all the time! I actually keep my homemade ketchup chunky because I'm too lazy to even pull out my food processor, but I might just have to convince myself to (literally) give it a whirl sometime. :)
  4. says

    Oh gosh, this looks delicious. Though I can imagine the struggle that went into it! When faced with 25 pounds of anything, it can get stressful. Luckily you managed to create this delicious-looking recipe, plus no more fake tasting store-bought ketchup! :)
  5. M Benton says

    I made this ketchup today and it is delicious. It is the perfect blend of vinegar spice and sugar. I will definitely make this again. I am always amazed that a large amount of produce cooks down so much, but the concentrated result is very good.

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