In a large soup pot, heat olive oil over medium-high heat. Add onions and cook, stirring, until they start to sweat, about 5 minutes. Add garlic and both the sweet and hot pepper.
Stir to combine and reduce heat to medium. Cook the vegetables, stirring occasionally, for another 15 minutes, until they're softened and aromatic. Add cumin, tomato paste and smoked paprika, and stir until combined, and vegetables have taken on a warm and rosy glow.
Stir in the black beans and about 1 cup of the bean cooking broth. Reduce heat to medium, set the pot lid on halfway, leaving a little steam vent. Cook the beans for an hour, longer if you've got the time. Add more bean broth, 1/2 cup at a time, if beans seem dry. Aim for thick, not over-dry. The goal is a divine beanly sludge.
Stir in the sherry or cider vinegar. Remove from heat.
Add the chiffonade of kale or chard by the handful. Stir gently, letting the greens wilt into the beans.
Season generously with sea salt to taste.