I couldn't find much in the way of recipes, so I ended up making one up. I did figure out that they are native to Peru.
I put them in the slow cooker covered with several inches of water. I added a chopped onion, some chopped garlic, 2 tsp. of cumin, 1 tbsp. salt, and 1/2 tsp. pepper. Pretty simple. I cooked it on low all day (check around midday to make sure they don't need more water), until the last hour, when I turned it up to high.
They were very tasty - similar to pintos.
Readers, have you ever tried Mayocoba beans?