Step 1

Preheat oven to 425°F. To make the crust, place a steamer insert in a saucepan over 1 or 2 inches of water. Cover pan, and bring to a boil over medium-high heat. Add the potatoes, cover, and steam for about 10 minutes, until the potatoes are very tender when pierced with the tip of a sharp knife. Remove the pan from the heat, and transfer potatoes to a large bowl to cool. Mash the potatoes well with a potato masher.

Step 2

Mix together the oat and almond flours, flaxseed, rosemary, salt, and baking powder in a bowl. Add the potatoes, and mix well with a spatula or by hand, to bind the dough; if needed, add up to 3 tablespoons of water in 1-tablespoon increments. Without kneading, gather the dough into a ball; it should have a crumbly-flaky texture.

Step 3

Divide the dough into two equal portions. Line a wood cutting board with plastic wrap, and lightly dust the plastic with oat flour. Place one portion of dough on the plastic, cover it with a second piece of plastic, and roll out the dough to a 10- to 11-inch disk. Lay the dough in a dry pie dish, pressing up the sides to the edge of the dish. Poke dough with a fork a couple of times. Bake for 20 minutes.

Step 4

Meanwhile, roll the second portion of dough out to a 10- to 11-inch disk; set aside.

Step 5

To make filling, place the onions, mushrooms, and garlic in a saucepan and sauté over medium heat, stirring frequently, for 10 minutes or until the onions start to turn translucent. (There is no need to add water; the mushrooms will release enough liquid to prevent sticking.)

Step 6

Add the tomatoes, allspice, cinnamon, nutmeg, pepper, and cloves, and let the mixture cook for another 5 minutes.

Step 7

Add the frozen vegetables, nutritional yeast, oat flour, lemon juice, and salt and pepper to taste. Mix well. Cook for another 5 minutes.

Step 8

Pour the filling into the pie crust. Lay the top crust over the filling, and crimp the dough around the edges. If there is any dough left over, shape it into leaves or use cookie cutters to make decorations that can top the pie before baking.

Step 9

Bake the pie for about 60 minutes, or until golden brown. Remove from oven and let it sit for 10 minutes before cutting and serving.