Rinse the pinto beans under cold water using a colander to remove any debris.

Optional: Soak the beans in enough water to cover by 2 inches overnight, then drain and rinse before cooking.

Heat a tablespoon of oil in a large pot or Dutch oven over medium heat.

Add the chopped onion and sauté for about 5 minutes, until translucent.

Stir in the minced garlic, salt, black pepper, and cumin, and cook for 1 minute to bloom the spices.

Add the rinsed beans to the pot along with 4 cups of water or broth.

Increase heat to high and bring the mixture to a boil.

Reduce heat to low, add the bay leaf, cover, and simmer for 1 hour and 30 minutes to 2 hours, or until beans are tender.

Taste and adjust seasoning, then stir in diced ham or bacon if using, and cook for an additional 5 minutes.