make the sauce: heat the oil in a saucepan. add the onion, peppers, celery, and garlic. cook over medium heat, stirring continuously until the onions begin to brown. add in the spices and flour. quickly stir to incorporate and heat for another minute. add the vegetable stock and season with salt and pepper. bring the sauce to a boil. turn down the heat and allow the sauce to a simmer for 30 minutes to 1 hour, until the sauce is thick and the veggies are very tender.
when the sauce is just about done, spray a skillet with oil and heat over medium-high to high. add the tofu in one layer. flip the diced pieces after about 2 minutes, until a nice brown crispy skin covers the sides. transfer into the saucepan and stir to coat. can be served with rice or a nice piece of crusty bread... whatever you've got lying around and want to use up!