Ingredients 2   pounds   oxtails, cut into 2-inch pieces 2   small   yellow onions, finely choppe   1   cup   thinly sliced scallions (white and light green parts), plus sliced dark green tops, for garnish .3333   cup   packed light brown sugar 2   tablespoons   soy sauce 2   tablespoons   ground allspice 1   tablespoon   black pepper 1   tablespoon   Worcestershire sauce   2 ½   teaspoons   kosher salt, or to taste 4   medium   garlic cloves, smashed 2   fresh Scotch bonnet chiles, stemmed and chopped 1 ¼   cups   dried butter beans 2   tablespoons   vegetable oil   4   cups   water, divided 2   teaspoons   fresh thyme leaves 3   medium   carrots, chopped into 1 ½-inch pieces   Directions Combine oxtails, onions, white and light green scallion slices, brown sugar, soy sauce, allspice, black pepper, Worcestershire sauce, salt, garlic, and chiles in a large bowl; toss to coat. Cover with plastic wrap. Place beans in a separate large bowl; add cold water to cover by about 3 inches. Cover with plastic wrap. Place both bowls in refrigerator for at least 8 hours or up to 12 hours. Drain beans; set aside until ready to use. Heat oil in a large Dutch oven over medium-high until shimmering. Using a slotted spoon or tongs, add oxtails, reserving marinade in bowl. Cook oxtails, turning occasionally, until evenly browned on all sides, about 15 minutes. Remove from heat. Remove oxtails from Dutch oven, and set aside. Discard drippings, and return oxtails to Dutch oven. Add beans, reserved oxtail marinade, 3 cups water, and thyme. Cover Dutch oven; cook over low, stirring mixture and turning oxtails every 30 minutes and adjusting heat as needed to maintain a very low simmer, until meat is tender when pierced with a paring knife but not yet falling apart, about 2 hours. Add carrots to oxtail mixture; uncover and cook over low, undisturbed, adjusting heat as needed to maintain a very low simmer, until carrots are tender, meat easily pulls away from bone with a fork, and sauce starts to thicken, about 45 minutes, skimming fat from surface as needed. Gradually stir in up to remaining 1 cup water as needed until sauce reaches a gravy consistency. If desired, remove oxtails from pot; shred meat and discard bones. Stir shredded meat back into pot. Divide mixture evenly among bowls; garnish with reserved dark green scallion slices. Make Ahead Oxtails can be made up to 3 days ahead.