Preheat oven to 375°F (190°C).
Cook the filling: In a skillet, heat oil over medium heat. Sauté onion (and bell pepper, if using) for 3–4 minutes. Add garlic, plant-based meat, and seasonings. Cook until browned. Stir in beans, corn, tomatoes (or sauce), and simmer for 5–7 minutes until thick. Taste and adjust seasoning. Stir in vegan cheese if using.
Assemble: Pour the filling into a greased 9x9 or 9x13 baking dish. Prepare cornbread mix according to package, then spread evenly over the filling.
Bake for 25–30 minutes, or until cornbread is golden and cooked through.
Cool slightly before serving. Garnish with chopped cilantro, avocado, or vegan sour cream.
