Step 1: Begin by warming the sunflower oil in a pan over medium heat. Gently sauté the finely chopped onion for about 5 minutes until it softens and becomes translucent, releasing a sweet aroma. Sprinkle in the hot chilli powder and ground cumin, frying for an additional minute to bloom the spices and deepen their flavor. Next, add the minced beef to the pan. Stir and break it apart, allowing it to brown evenly for several minutes. Stir in the rich tomato purée, beef stock, and a pinch of ground cinnamon, which adds a subtle warmth to the chili. Bring the mixture to a brisk boil, then reduce the heat to a gentle simmer. Let it cook uncovered for 15 to 20 minutes, stirring occasionally until the sauce thickens and most of the liquid evaporates, leaving a thick, hearty filling. About 5 minutes before the end of cooking, fold in the kidney beans to warm through without losing their shape. Taste and adjust seasoning if needed, then set aside and allow the mixture to cool. Step 2: Preheat your oven to 200°C (180°C fan, gas mark 6). Using a 7cm pastry cutter, cut out 12 neat circles from the ready-rolled shortcrust pastry. Gently press each circle into the wells of a 12-hole mini muffin tray, making sure to create an even pastry base and sides. Prick the base of each pastry case lightly with a fork to prevent bubbling during baking. Bake the cases for 10 minutes until the pastry begins to set and turns a pale golden hue. Carefully remove them from the oven and transfer to a wire rack to cool. Repeat this process with any remaining pastry. Step 3: While the pastry cases cool, cook the potato in boiling water until tender when pierced with a fork, approximately 15 minutes. Drain well and mash the potato until smooth and fluffy. Stir in the sour cream for creamy richness, season lightly with salt and pepper, and fold through the chopped chives for a fresh, herbaceous note. Spoon 1 to 2 teaspoons of the chilli beef mixture into each pastry case, then top each with a teaspoon of the chive mashed potato. Use a fork to ruffle the surface of the mashed potato, adding a textured finish that browns beautifully in the oven. Return the pies to the oven and bake for a further 15 minutes until the potato topping is golden and the filling is bubbling. Serve warm and enjoy the comforting, spicy flavors! Tip: For an even crisper base, consider blind baking the pastry cases by lining them with parchment paper and weights (or dried beans) before the initial bake. This helps prevent sogginess when filling them later. Additionally, prepping the filling a day ahead improves the flavors as they meld overnight.