Begin by washing and rinsing the dried kidney beans thoroughly. Place them in a deep bowl and cover generously with water, remembering that the beans will swell to at least triple their original size during soaking. For best results, soak the beans overnight or for a minimum of 2 hours to shorten the cooking time later. Once soaked, discard the soaking water. Next, have your butcher cut the salted pigtail into manageable 2-inch pieces, as these can be tough to slice with a regular kitchen knife at home. Rinse the pigtail pieces well. In a deep pot, bring water to a boil, add the pigtail, and cook them for 20 minutes to start tenderizing and leach out excess salt. Drain, rinse, then repeat the boiling process once more with fresh water. Now, it's time to assemble the soup. Place the soaked kidney beans, prepared salted pigtail, diced onion, chopped red peppers, spring onions, garlic, thyme sprigs, black pepper, allspice, carrots, and beef into a large pot. Cover everything with water and bring the mixture to a rolling boil over high heat. As it boils, skim off any froth or scum that rises to the surface and discard it. Reduce the heat to maintain a gentle boil and cook uncovered for approximately 1 hour and 15 minutes, or until the beans are tender and beginning to break apart. Add diced potatoes and coconut milk to the pot, stirring gently to combine. Continue cooking for an additional 15 minutes, allowing the potatoes to soften and the flavors to meld. While the potatoes cook, prepare the dough for the spinner dumplings. Mix the plain flour and water in a bowl, adding a pinch of salt if desired, until you achieve a soft, smooth dough. Let the dough rest for 5 minutes. Pinch off small portions (about a tablespoon each) and roll between your palms into thin, cigarette-like shapes. Drop the dumplings into the boiling soup, stir well to distribute them evenly, and cook for another 15 minutes on a rolling boil. The dumplings will puff up and cook through, adding a delightful chewy texture to the soup. Taste the soup near the end of cooking. Owing to the salted pigtail, additional salt may not be necessary, but adjust seasoning to your preference. Remember, this flavorful soup thickens considerably as it cools, so keep that in mind when serving. Tip: To save time, soak your beans overnight in the refrigerator and prepare the pigtail a day ahead if possible. This will make the cooking process smoother and enhance the flavors as they develop. Enjoy your comforting bowl of Red Peas Soup with a side of rice or fresh bread for a satisfying meal.