Rinse the pinto beans with cold water.
Place beans and 6 cups of water in a pot.
Bring to a boil, then reduce heat.
Simmer, covered, for about 2 hours.
Check beans occasionally, add water if needed.
Heat oil in a pan over medium heat.
Add diced onion, cook until clear.
Stir in minced garlic and chopped jalapeño.
Sauté for 1 minute until fragrant.
Add the sautéed mixture to the cooked beans.
Continue cooking on low heat.
Mash beans with a spoon or masher.
Season with salt to taste.
Add water if beans are too thick.