Remove the seeds and stems from the remaining ½ green pepper on a cutting board. Leave the seeds in the ajícitos (sweet chili peppers). With the chef's knife, dice the peppers and onion.
Using the flat side of the knife, smash the garlic cloves, splitting the skins and releasing the oil for easy peeling. Mince the garlic cloves. Add ¼-½ tsp of salt to the garlic, hold the blunt side of the knife with both hands, and with your knife at a slight angle, drag the sharp edge across the garlic (pulling towards you) to make garlic paste.
In a sauté pan, add ½ cup Spanish olive oil over medium heat and heat the oil for about 2 minutes. Test the heat by adding 1 dice of the green pepper; if the oil sizzles, it's ready.Add the rest of the diced peppers, onion, garlic paste, ½ tsp salt, ½ tsp pepper, and ½ tsp ground cumin. Stir frequently so that the garlic doesn't burn and cook until soft and the onions are translucent, approximately 6-8 minutes. This medley is known as sofrito. Taste the beans. Check if they are soft and have the desired mouthfeel. They should "melt." Otherwise, add 2 cups of hot water, boil for 30 more minutes and check again. Repeat if necessary.
Once the beans are soft, add the sofrito from the sauté pan, ½ cup vino seco (dry cooking wine), and 3 culantro leaves. Taste for salt and adjust according to your personal taste.
Optional: Add ½-1 tsp granulated sugar.
Cook to thicken the beans. You will know when the beans are sufficiently thick when they should coat the mixing spoon.