Place fat, flour, salt, and pepper into a 10 to 12-inch skillet. Cook until dark brown stirring continuously. Add onions and continue stirring until onions are tender.
Add can of Rotel tomatoes and milk. Continue cooking until gravy is as thick as you like gravy. If it starts to getting too thick, thin with additional milk. Serve on rolls, biscuits, corn bread or mashed potatoes.
Servings: 3 1/2 cups