Method
1. Juice 1 lime into a large, non-metallic bowl. Add a pinch of cayenne (use as much or as little as you prefer) and a pinch of salt. Stir together. Pat the chicken thighs dry with kitchen paper and remove any visible sinews. Chop into bite-sized chunks. Add to the marinade and turn to coat. Set aside for 20 mins.
2. Meanwhile, peel and grate 6 garlic cloves. Peel and grate 25g of the ginger. Scoop them into a small bowl. Add the garam masala, ground coriander and 100g of the yogurt. Add 2 tbsp oil and a pinch of salt and pepper. Stir well to mix. Add the yogurt marinade to the chicken. Stir well to coat. Marinate at room temperature for 1 hr or cover and marinate in the fridge for 12-24 hrs.
3. To make the sauce, place a large pan on a medium heat and add the cumin seeds. Toast for 1-2 mins, shaking the pan, till aromatic. Tip into a small dish. Add the cinnamon stick and toast for 1-2 mins, turning occasionally, till aromatic. Tip into the dish with the cumin. Set aside. Also set the pan aside for later.
4. Peel and finely chop the onions. Place the pan back on a medium heat. Add 50g of the butter and 2 tbsp oil. Swirl to melt, then add the onions. Fry, stirring often, for 15 mins till the onions are soft and browned.
5. Meanwhile, peel and grate 6 garlic cloves and 25g ginger. Finely chop the chillies, discarding the seeds and white pith if you prefer less heat.
6. Add the garlic, ginger and chillies to the onions. Fry, stirring, for 2-3 mins till aromatic. Add the cumin and cinnamon stick with 8 cardamom pods and 2 bay leaves.
7. Pour in the passata. Add 200ml water. Stir well, then bring to the boil. Turn the heat down. Pop on a lid. Simmer for 15 mins, stirring occasionally, to mingle the flavours. Pick the bay leaves, cinnamon stick and cardamom pods out of the sauce. Blitz the sauce in a blender – or use a hand-held blender. You can also leave the sauce unblended, if you prefer.
8. Meanwhile, take the chicken out of the fridge. Preheat your grill to high. Line a grill pan or baking tray with foil.Lift the chicken out of the marinade, shaking off any excess, and thread onto skewers. Place on a rack on the tray and grill for 30-40 mins, turning regularly, till the chicken is golden brown and cooked through.
9. Slide the grilled chicken off the skewers into the sauce. Simmer for 5-10 mins till the sauce has thickened. Pour in 150ml of the cream. Squeeze in the juice from the remaining lime. Add 50g butter. Stir to mix and gently warm through. Taste and add salt and pepper or a pinch of sugar, if needed.
10. Finely slice the mint leaves while the curry warms. Ladle the curry into a serving dish and garnish with the sliced mint. Serve straight away.
11. Get Ahead
You can marinate the chicken for up to 24 hrs. Longer is better to help the flavour develop and tenderise the chicken. You can also make the tomato sauce the day before. Cool and store in the fridge, then reheat while you’re grilling the chicken.
12. Love Your Leftovers
The Butter Chicken will keep in the fridge for up to 3 days. Cool and store the curry in an airtight tub. Reheat on the hob or in the microwave, adding a splash of water or chicken stock to loosen the sauce.