Cook the beef filling. Place a large frying pan over medium-high heat and add the olive oil. Once the oil shimmers and ripples, add the beef mince. Break it apart with a wooden spoon and let it brown undisturbed for 2-3 minutes. You'll hear a satisfying sizzle—this is the sound of browning. When the meat turns a deep golden brown and releases a rich, savoury aroma, stir it to break up any large clumps. The bottom of the pan should have a lovely brown fond (that's flavour!).

Sweat the aromatics. Reduce the heat to medium and push the beef to one side of the pan. Add the diced onion to the empty space and cook for 2-3 minutes until it turns translucent and softens, releasing a sweet fragrance. Stir in the minced garlic, cumin, smoked paprika, oregano, salt, and pepper. Cook for another 30 seconds until the spices become fragrant and coat the beef. You'll notice the colour deepen as the paprika blends in.

Simmer the filling. Add the tomato purée and stir it through the beef mixture for 1 minute, letting it caramelise slightly. Pour in the beef stock, scraping the bottom of the pan with your spoon to lift all those browned bits. Let the mixture simmer gently for 3-4 minutes until the liquid has mostly evaporated and the filling looks thick and glossy, not watery. The texture should be moist but not saucy—you don't want soggy tortillas. Remove from the heat and stir in the fresh coriander if using.

Prepare the quesadillas. Wipe the pan clean and return it to a medium heat. Place one tortilla flat on a cutting board. Sprinkle half of the cheese mixture evenly over half of the tortilla, leaving a small border at the edge. Spoon a quarter of the beef filling over the cheese, then add any optional bell pepper slices. Top with the remaining cheese—this is the glue that holds everything together. Fold the empty half of the tortilla over the filling, pressing down gently. The tortilla should look plump and slightly heavy.

Cook the first side. Place the folded quesadilla in the dry pan (no oil needed if using a non-stick pan). Cook for 2-3 minutes. You'll hear a gentle crackle as the tortilla hits the heat. When the bottom turns a deep golden brown with darker speckles and feels crisp to the touch, it's time to flip. The cheese inside should be just starting to melt—you might see a little oozing at the seam.

Cook the second side. Carefully flip the quesadilla using a spatula. Cook for another 2-3 minutes until the second side is also golden brown and crisp. The cheese should be fully melted and stretchy—when you press the top with a spatula, it should feel firm but give slightly. The aroma of toasted tortilla and melted cheese will fill your kitchen. Repeat with the remaining tortillas and filling.

Rest and slice. Transfer the cooked quesadillas to a cutting board and let them rest for 1-2 minutes. This short rest allows the cheese to set slightly, making slicing cleaner. Use a sharp knife or pizza cutter to cut each quesadilla into three wedges. You'll see the cheese stretch beautifully between the pieces. Serve immediately while the outside is still crisp and the inside is hot and gooey.