Preheat the oven to 350°F.
Add the firm tofu to a food processor along with the cornstarch, nutritional yeast, turmeric, onion powder, garlic powder, salt, black salt (kala namak) and soy milk and process until smooth. Set aside.
Now add the chopped onion and crushed garlic to a pan* with the olive oil and sauté until softened.
Add in the sliced cremini mushrooms and chopped red bell pepper and sauté until softened.
Add the baby spinach and stir in until just wilted.
Now add in your tofu mix and fold it in with the veggies. If your skillet is oven safe then you can just smooth down in the pan and bake it directly in the pan. If not, then transfer this to an 8-inch or 9-inch pie dish and smooth down.
Top with some sundried tomato pieces and red onion for decoration (optional).
Bake in the oven for 40 minutes until firm and golden on top.
Allow to cool for 10 minutes before slicing.