Cover the tofu in the vegetable broth and soy sauce, and let it sit to marinate while you're chopping the vegetables.
In a large pan, heat 2 tbsp olive oil over medium heat. Add the onion, carrots, and garlic. Stir and cook for about 5 minutes until the onions start to brown.
Add the mushrooms and cook for a few more minutes until tender.
Stir in the gluten-free flour and cook, stirring often, for 2 minutes. Whisk in the marinade from the tofu as well as the lemon juice, making sure there are no lumps. Stir until smooth.
Next, add the potatoes, drained tofu, thyme, sage, salt, and pepper. Bring the stew to a boil then turn it down to a simmer. Stir occasionally and cook for about 20 minutes until the potatoes are tender.
Finally, add in the peas and coconut milk. Taste and adjust the seasoning if necessary, then pour into to a greased 9″x13″ baking dish.
For the biscuits, mix together the oat flour, coconut sugar, baking powder, baking soda, and salt.
Add the chilled vegan butter to the dry ingredients and use your hands to crumble the vegan butter into the dry ingredients until the mixture resembles fine crumbs.
Add 1/2 cup of soymilk and use a fork to stir it all together, being careful to not overmix. If it's too dry and not coming together, you can add up to 1/4 cup more soymilk. As soon as the mixture is just combined, use a large spoon to scoop out lumps of biscuit dough to place on top of the stew in a 4×3 pattern.
Bake at 400F for 25 minutes until the biscuits are golden brown on top and cooked all the way through. Enjoy your biscuit pot pie hot from the oven!