Sauté onion, garlic, green pepper, and mushrooms in vegetable oil for 3 minutes. Add vegan sausage (optional) and sauté for 1 minute.
Mix in tofu and all remaining ingredients except fresh tomatoes. Cook over medium heat, stirring occasionally, until hot.
Add tomatoes. Cover and cook for 2 minutes or until tomatoes are heated through. Serve in warm, corn tortillas.