1: Preheat the oven to 190°C/Fan 170°C/Gas 5. Put the mince in a roasting tin and roast for about 40 minutes, turning every 10 minutes or so, to get a very dark, even colour all over the meat. It should be crispy and resemble instant coffee granules. You can colour the meat in a large frying pan on the hob if you prefer; just keep stirring until it is dark brown. Drain in a colander and set aside.
2: Preheat the grill to high. Place the tomatoes, cut side up, on an oven tray and grill until caramelised, about 6–8 minutes. Set aside.
3: Place a large heavy-based pan over a medium-low heat and add a good splash of oil. Add the onions and garlic and sauté, stirring from time to time, until softened, about 10–15 minutes.
4: Add the chorizo and cook until some of its fat renders and colours the onions. Stir in the cumin seeds, chilli powder, cracked black pepper and ground coriander. Cook, stirring occasionally, for 5–6 minutes.
5: Stir in the celery, browned mince and grilled tomatoes. Pour on the beef consommé and bring to the boil. Lower the heat to a simmer and cook gently, uncovered, for 1–1½ hours, until thickened to a rich chilli. Stir in the green chillies and lime juice, season with salt and remove from the heat.
6: To cook the beans, melt the butter in a pan over a medium-high heat. Add a good splash of water and some salt and pepper. Tip in the green beans and cook for 3–4 minutes until they are just tender. Remove from the heat and stir in the yoghurt and chopped mint.
7: Divide the green beans between warmed bowls, spoon on the chilli and grate some chocolate over the top to serve.