Put the GF flour in the bowl of a food processor with a blade attachment. Add the other dry ingredients and pulse the machine a few times to mix them together.

Add the cubed butter and lard and pulse the machine until the fat is size of small peas mixed with the flour.

Mix the water, vinegar and egg together in a small bowl and pour it into the flour mixture in the food processor.

Pulse the machine until the dough starts to come together into a ball.

Turn the loose ball of dough onto a floured board. Gently knead it so that it comes together in a ball. Divide the ball in two and flatten each half into a disc. Wrap each disc in plastic wrap and put them in the fridge for at least a half an hour.

Place a large piece of wax paper on a large board and dust it well with flour. Place one disc of dough on the piece of floured wax paper and dust the top of the dough well with flour. Place another large piece of wax paper on top of the dough and roll it out with a rolling pin.

Frequently lift the piece of wax paper off and dust with flour again. Lift the bottom piece of wax paper up on one side and gently reveal the underside of the dough and dust it with flour. Do the same on the other side.

Put the piece of wax paper back on top and continue to roll the dough until it is 3mm thick. Remove the top piece of wax paper.

Using the rolling pin and the bottom piece of wax paper to help you, roll pie dough around the rolling pin and gently lift the dough over top of the pie plate. Unroll the dough over the pie plate. If it cracks, just press it back together with your fingers.

Gently shift the pie crust into the pie plate and press down. Try not to stretch it into the pie plate because it will crack if you do that.

Roll out the second piece of dough in the same manner as the first. Set it aside in the fridge or on the counter while you prepare the filling.

Preheat the oven to 425F

In a large bowl, stir together the frozen black raspberries and cherries, cornstarch, sugar and lemon juice.

Pour berry mixture into the prepared bottom pie crust.

Brush the edge of the pie crust with beaten egg.

To place the top crust on the pie using the rolling pin method described above. If you are feeling adventurous you can put one hand under the pie dough still on the wax paper, hold one edge of the wax paper so that the top arm crosses over your bottom arm and flip the pie dough over top of the filling and bottom dough.**

Press the top dough around the edge so the two crusts stick together. If there are any cracks press them together with your fingers. Use a knife to cut off the overhanging dough.

Crimp the edge of the crust by pinching the dough with your index fingers the same time you push the dough between your index fingers with your thumbs.

Brush the top of the dough lightly with the beaten egg. Make two v-shaped cuts in the centre of the pie. Sprinkle the pie with course sugar (optional).

Place a piece of foil on the bottom of your oven to catch drips.

Place in the oven at 425 F for 20 minutes, then reduce the temperature to 350 F for an additional 50-60 minutes, or until the filling is bubbling in the centre.