Brown meat and onion in a large skillet over medium-high heat (350 degrees F in an electric skillet). Drain fat.
Add beans, tomatoes, corn, one tablespoon chili powder, cumin, garlic powder, oregano, salt, and pepper. Reduce heat to low (250 degrees F in an electric skillet), cover, and heat thoroughly.
As the mixture heats, mix cornmeal, salt, sugar, and one teaspoon chili powder with water in a small saucepan. Cook over medium heat, stirring constantly until thickened, about two minutes. Add cheddar and mix well.
Spread cornmeal mixture over chili mixture. Cover and cook over low heat, with lid slightly ajar, until topping is set, about 10 minutes.
Serve immediately. Refrigerate leftovers within 2-3 hours.
