Drain and rinse the beans.
Heat a 9-quart dutch oven over medium-high heat. Add 2 tablespoons of vegetable oil and saute the onion for 5 minutes. Add cumin, chili powder, and garlic and saute for an additional minute.
Add the drained beans, 1 tsp. salt, and two quarts of water. Bring to a boil, then reduce to a simmer. Cover and simmer for two hours.
Remove lid and simmer until the beans are soft and the liquid has reduced to a gravy-like texture. Drain, reserving liquid.
Preheat a large frying pan over medium-high heat. Add 1/4 cup of lard. Once completely melted, add drained beans. Mash with a potato masher or the back of a large spoon while cooking. Add enough of the cooking liquid to reach your desired consistency. Cook, stirring and mashing constantly for 4-5 minutes. (Note: Some chunks are good. You don't want a bean puree.)