To make the hot water pie crust (use premade to skip this step)
Mix the dry ingredients (1 1/2 cups flour, 1/4 tsp baking soda, 3/4 tsp salt) in a bowl. Then pour in 1/2 cup of oil and 3 tbsp of boiling water. Mix well until it forms a ball.
Place the dough ball on a piece of parchment paper and press it out flat. Cover with the second piece of parchment paper.
Use a rolling pin to roll the dough out flat between the parchment sheets, then peel off the top sheet. Use the bottom piece of parchment to flip the crust onto the pie dish, then peel off the second piece of parchment.
Pinch the edges to form an even crust around the top of the pie dish.
Make the vegan quiche filling
Preheat your oven to 400°F (200°C).
Dice 1 medium onion and saute it in 1 tbsp of oil over low heat until translucent.
Add 2 cups diced mushrooms, sprinkle with 1/2 tsp salt, and continue to saute until they begin to release their juices.
Add 5 oz of baby spinach and stir for a few minutes until the spinach just barely wilts, then turn off the heat.
Break up 2 packages of tofu into smaller pieces so it fits in your food processor. (You may have to do this in 2 batches if you don't have a large food processor.)
Add 1/2 cup nutritional yeast, 1/4 cup melted margarine, 2 tsp salt, and 1/2 tsp pepper to your food processor, then blend. (It will turn into a crumbly, grainy mixture).
Slowly add 1/4-1/2 cup soy milk, 1 tbsp at a time, blending between each tbsp until the tofu mixture turns from crumbly to a very thick paste. (If you don't use the high-protein tofu, you may not need much milk.)
Add the tofu mixture to the sauteed veggies along with 2/3 cup vegan cheese and 2/3 cup vegan bacon bits. Mix well.
Pour the combined tofu-veggie mixture into your formed pie crust and pack the tofu down firmly and evenly in the pie dish.
Bake at 400°F (200°C) for 1 hour.
Brush the top of the quiche with an additional tbsp of melted margarine if desired for a shiny glow.
Let it cool for about 10 minutes before cutting to allow it to set a little and firm up.
Notes
This makes a large quiche! It fills a 9-inch pie dish to the top.
If you are using a small, ready-made pie crust, you may want to cut the recipe in half.
You can find packs of 2 ready-made vegan pie crusts in tins at most grocery stores. This recipe fills those 2 ready-made crusts perfectly.