Wash and chop the vegetables. Cook in water until firm to the bite.
Peel sweet potatoes and cut into thin slices.
Finely puree tofu, soy drink and yeast flakes in a blender.
Pour the mixture into a saucepan. Add 100 ml of water and bring to a boil. To thicken the liquid, mix the starch in a cup of cold water, add to the liquid and bring to the boil.
Season with onion powder, garlic powder, turmeric, salt and pepper, and a splash of soy sauce.
In a baking dish first fill half the can of tomatoes. Season with salt, pepper and oregano.
Spread the thin slices of sweet potato on top of the tomato sauce.
Then add the drained vegetables on top of the sweet potatoes.
Cover the vegetables again with a layer of sweet potatoes.
Finally, cover with the tofu sauce.
Bake in preheated oven at 200 degrees celsius top/bottom heat for about 40 minutes.