Growing up my momma made pinto beans 2x a week. This is how she showed me.
Get a SS pot add the hock and onions. Cover hock with water and bring water to a broil for 2 hours. Pull the hock and take meat off cut into chunks. Add back to water.
Hock and onions ready to cook.
Sort the dry beans 1lb. Take out any rocks or ugly color or bad bad beans.
Cut the hock meat down and add to water. Keep a pan of hot water on the stove to add to beans when liquid gets low. You want to keep about 1" of liquid over the cooking beans.
Take the dry beans, place in container and rinse with cold water 3x. This will take off the dirt and any bean skin.
Add dry beans to hock water.
Simmer uncovered from 4-6 hours or until beans are fork tender. You can add cumin, garlic, black pepper at any time but NO SALT YET.