Step 1: Begin by crafting a deeply flavored stock. Place the beef shin, a whole unpeeled onion, bay leaf, and 2 litres of lightly salted cold water in a large saucepan. Simmer over very low heat gently for about 1 hour and 30 minutes, or until the beef shin is meltingly tender and easy to shred — bear in mind this could extend up to 3 hours for ideal tenderness. Remember to skim off any foam or scum that rises to the surface to keep your broth clear and delicious. Once the beef is soft, break apart any large pieces into the broth. Remove and discard the whole onion. Step 2: Next, introduce the peeled and chopped potatoes into the broth. Season generously with salt and pepper, then cook for 10 to 15 minutes until the potatoes are tender and soak up the savory flavors. While the potatoes cook, gently warm the sunflower oil in a large, deep frying pan over medium heat. Add the diced onion and carrot, then stir frequently until the carrot softens and begins to caramelize, releasing its natural sweetness — a vital step that enriches the soup's complexity. Step 3: Incorporate the beetroot into the pan and cook for about 5 minutes, stirring occasionally to prevent sticking. If using, add the chopped red pepper and sauté for another 2 minutes. Then mix in the tinned tomatoes and prunes, stirring well. Turn up the heat to bring the mixture to a boil, letting the liquid reduce slightly, concentrating the flavors, before transferring everything into the borscht stock. Step 4: Finally, fold in the shredded white cabbage and the drained kidney beans. Continue simmering for 7 to 10 minutes until all the vegetables are tender and have melded together beautifully. Serve the finished borscht piping hot, topped with a generous dollop of crème fraîche or sour cream. Sprinkle with freshly chopped dill for a bright, herbal note, and accompany with crusty bread for dipping, making each spoonful deeply satisfying and comforting.