In a large skillet over medium-high heat add oil. Add onion and sauté until soft (about 5 minutes). Add garlic, chili powder, oregano, and cumin. Stir and sauté for 1 minute.
Add ground beef and cook stirring often until it loses its raw color. Break ground beef up with a spatula into small chunks while cooking. Stir in tomatoes, and simmer for 5 minutes. Add salt and pepper. Stir in cornmeal and cook stirring constantly until the mixture has become thick.