Place beans in an Instant Pot insert or other pressure cooker along with the ham hock (if using). Cover with at least 2" of water (more is OK).
In an Instant Pot, use the 'Manual' button and select 20 minutes. May be called 'pressure cook" on newer models (any high pressure program for 20ish minutes is fine). *Stovetop directions below in 'notes'*
When the time is up, hit 'cancel'. Wait for the pressure to come down naturally, or do a quick release as preferred. The beans will continue to cook in the next step.
Without draining the bean broth (add more broth or liquid if it doesn't seem soupy, we will be boiling off more liquid now as they cook some more), mix in the pepper, onion, minced ham.
Hit 'sauté" and keep hitting until the the 'low' setting is selected. Simmer, uncovered for 1-3 (or more!) hours, or until most of the water is evaporated and the beans are melt-in-your-mouth tender. I use the 'low' sauté feature so it is not a vigorous bubble which will splatter annoyingly!
Keep careful watch on your water level, and add more liquid if you need to. I like to leave my beans a little bit saucy, but this up to you! You could also choose to mash them up a bit for a refried-style.
Finally, stir in the tomato paste or sauce, sea salt, and the cumin/chili powder as you like.
DUTCH OVEN METHOD : In a large Dutch oven style pot large enough to accommodate all the your soaked beans and enough water to have at least 1-2" of water above beans. Bring the soaked pinto beans to a boil, reduce heat to low and simmer (covered) for 3-4 hours until tender. They should be simmering only (not bubbling vigorously). Continue with steps 8-10 above.
Recipe via tessadomesticdiva.com