Rinse pinto beans in a colander, removing any unwanted pebbles or pieces that may be in the bag.
Add the beans, onion, and salt to the instant pot and fill the pot with about 7-8 cups of water.
Pressure cook. Turn valve to sealed and cook on high pressure/manual for 45 minutes. Allow the pressure to naturally release for 25 minutes. Remove lid and test beans to make sure they are tender.
Sauté beans. Drain the beans, removing the onion and reserving ½ cup of the bean broth water. On SAUTE mode, add lard or oil. Once hot, add the garlic and stir. Add the beans, cumin, oregano and ¼ cup of the bean broth. (You could also chop the reserved onion and add it to the pan).
Mash. Cook, gently smashing the beans as they cook with a potato masher or fork. Continue stirring and mashing until you get the texture you like and the beans are the consistency of soft mashed potatoes. Add more bean broth liquid if necessary. Taste and season with additional salt if needed.
Serve. Top with shredded cheese, if desired.
