Place 2 cups dried black beans (no need to soak) in a colander and rinse under cold running water. In a large stockpot, combine drained black beans, 2 tbsp. extra-virgin olive oil, and 8 cups water to cover the beans. Bring to boil over high heat and cook 15 minutes.
Reduce heat to low, cover, and simmer beans, checking occasionally and adding more water if needed to keep covered, until tender but not mushy, 1½ – 2 hours. Squeeze a bean between your fingers to test.
Meanwhile, peel and finely chop 1 large onion; set aside for mayi moulen. Thinly slice 5 scallions. Smash 8 garlic cloves with the side of chef’s knife, peel, and finely chop. Remove leaves from 10 sprigs parsley and 6 sprigs thyme and coarsely chop: discard stems.
Purée most but not all the beans in pot with an immersion blender (or transfer about half of the beans to a regular blender and blend until mostly smooth; mix back into beans in pan).
Heat 2 tbsp. extra-virgin olive oil in a small skillet over medium. Cook scallions and a little less than half of the garlic, stirring often, until starting to brown, about 4 minutes. Scrape into beans, then add half of the parsley, half of the thyme, ¾ cup unsweetened coconut milk, and 2 tsp. sea salt.
Drop the habanero chile or the jalapeno peppers into the beans. Bring bean mixture to a simmer. Cook, stirring occasionally, until just beginning to thicken (but don’t cook so aggressively that chile breaks open), 15–20 minutes. Sos pwa nwa should still be loose enough to spread on a plate. Thin with water if needed. Taste and season with more salt as needed. Carefully fish out and discard chile.
Meanwhile, make the mayi moulen: Heat remaining 2 tbsp. extra-virgin olive oil in a Dutch oven over medium heat. Cook reserved onion and remaining garlic, stirring often, until starting to turn golden brown, about 4 minutes. Add 4 cups water and bring to a boil.
Whisking constantly, gradually sprinkle in 1 cup cornmeal, then add remaining thyme, remaining parsley, and remaining 2 tsp sea salt. Cook, stirring constantly, until starting to thicken, about 2 minutes. Reduce heat to low and cover pot. Cook, stirring vigorously every 5 minutes orso, until cornmeal is velvety smooth and no longer gritty, 18–25 minutes. Tastemayi moulen and season with more salt if needed.