Rinse the pinto beans under cold water and remove any debris or stones.

In a large pot, combine the beans, onion halves, garlic cloves, bay leaf, and salt. Cover with water by about 2 inches.

Bring to a boil, then reduce heat to low and simmer for 1 to 1.5 hours, or until beans are very tender. Add more water if needed.

Drain the beans, reserving about 1 cup of the cooking liquid. Remove the onion halves and bay leaf.

In a large skillet, heat the lard or oil over medium heat. Add the cooked beans and mash with a potato masher or the back of a spoon.

Stir in the cumin and chili powder. Add reserved cooking liquid as needed to reach your desired consistency. Season with salt to taste.

Cook for another 5-10 minutes, stirring frequently, until the beans are creamy and well combined.