Brown ground turkey with garlic in a pot over medium-high heat. Add tomato sauce, Rotel, salt, oregano, cumin, and chili powder. Cover and reduce heat to low. Simmer for 30 minutes.
Mix corn meal with water, then add to the chili. Stir to combine and simmer for a final 10 to 15 minutes. Set aside.
Place Fritos in the bottom of an individual soup bowl. Pile in chili and cheese, and diced onion if using. Serve immediately.