Hominy is corn that has been dried and processed. Corn was first domesticated by the indigenous people of Mexico over ten thousand years ago, and it remains an essential ingredient in Mexican cooking to this day.
Heat the oil in a large nonstick skillet over medium heat. Sauté the onion until tender, 5 to 6 minutes. Add the hominy and tomatoes and stir to combine. Heat for 5 minutes.
Add the sauce and heat thoroughly. Pour into a casserole dish and sprinkle with the cheese. Serve immediately.