1. First, brine the chicken. To make the brine, mix the water and salt in a bowl until completely dissolved. Take a meat syringe and fill with 20ml of brine. Fold the skin at both ends of the breast up to reveal the flesh. Inject the brine in 6-8 places evenly through the breast, making sure not to break the skin. Repeat with 20ml more brine for the second breast. Fill the syringe with 15ml more brine and inject in 6 places evenly through the thighs and legs. Cover and refrigerate for 2-3 hours. If you don’t have a meat syringe, immerse the chicken in the brine and refrigerate for up to 4 hours.
2. To make the garam masala, preheat the oven to 130°C, and cover a baking tray with baking parchment. Cover the tray with the weighed spices and put in the oven for 90 minutes to toast. Remove from the oven and blitz in a small food processor or blender to a fine powder (in batches if necessary). Any leftover garam masala can be stored in an airtight container.
3. To make the marinade, put the tomatoes, garlic granules, garam masala and yogurt into a pan over a medium heat. Cook for 5 minutes, leave to cool and then blend. If you have a blender that can blend hot ingredients, you can blend first and then leave to cool.
4. Take the brined chicken and rub 100g of the marinade all over it, being extra careful of the fragile skin. Cover and leave in the fridge to marinate for 3 hours.
5. Cook according to pack instructions until the chicken is fully cooked through, with no pink meat and the juices run clear. Serve with raita and naan bread.