In a small skillet, cook onion and garlic in oil until tender. Remove from heat.
In a bowl, combine onion mixture, sour cream, half of the cheese, milk, chiles and cumin. Add hominy and mix well. Pour into a greased 2 quart baking dish. Bake, uncovered, uncovered at 350 degrees for 30 minutes or until heated through.
Sprinkle remaining cheese and put back in hot oven for 1 – 2 minutes. Remove from oven and serve immediately.