Soak the beans for at least 10~12 hours or overnight.
Now cook the beans along with the quartered onion, green pepper, 2 slit garlic cloves, ½tsp ground cumin, salt and pepper. Add water to reach 1" about the beans line. Bring the mixture to a boil, lower the heat and simmer for 1½~2hours or until the beans are very tender. Alternately beans can be pressure cooked until tender, for about 8~10 minutes. Then proceed with the recipe as mentioned below.
Remove the onions and peppers and grind them to a paste and add it back to the black beans and keep simmering.
Heat 2tbsp olive oil in a saucepan, add bay leaf, the remaining 2 finely minced garlic, finely chopped onion and green pepper. Cook till the onions are turning lightly brown and the peppers are tender.
Add the cooked onion mixture to the black beans along with apple cider vinegar, remaining ground cumin, salt and pepper. Cook for 10~15 minutes for the flavors to mingle, beans are tender and the broth gets nice and thick. Serve hot with some Cuban bread.