Slash the chicken’s legs a few times right down to the bone. Get a roasting tray slightly bigger than the chicken, then add all of the marinade ingredients and 2 level teaspoons of sea salt and mix together well. Put on a pair of clean rubber gloves, then really massage those flavours over and inside the chicken so it’s smeared everywhere. Don’t be shy! Ideally marinate overnight in the fridge.
Preheat the oven to 200°C/400°F/gas 6 and organize your shelves so the roasting tray can sit right at the bottom, the chicken can sit directly above it, right on the bars of the shelf, and the potatoes can go at the top. Halve any larger potatoes, then parboil them in a large pan of salted boiling water with a whole lemon for about 15 to 20 minutes, or until the potatoes are cooked through. Drain the potatoes then let them steam dry. Stab the lemon a few times with a sharp knife and put it right into the chicken’s cavity. Move the chicken to a plate.
Roughly chop the onions and add to the roasting tray along with the cinnamon stick, cloves, vinegar and Worcestershire sauce, then whisk in the flour. Pour in the stock or water, then place this right at the bottom of the oven. Place the chicken straight on to the bars of the middle shelf, above the roasting tray. Cook for 1 hour 20 minutes.
Put another sturdy roasting tray over a medium heat and add the olive oil, the mustard and cumin seeds, garam masala and turmeric – work quickly because if the fat gets too hot the mustard seeds will pop everywhere. Halve a bulb of garlic and add it straight to the pan, with the sliced chilli and chopped tomatoes. Add your drained potatoes to the tray, mix everything together, then season well. Finely slice and scatter in the coriander stalks, and keep the leaves in a bowl of water for later. After the chicken has been in for 40 minutes, put the potatoes in.
Once the chicken is cooked, move it to a board and carefully peel off the dark charred bits to reveal perfect chicken underneath. Pass the gravy through a coarse sieve into a pan, whisking any sticky goodness from the pan as you go. Bring to the boil and either cook and thicken or thin down with water to your preference. Put it into a serving bowl and drizzle over a little yoghurt. Get your potatoes out of the oven and put them into a serving bowl, then serve the chicken on a board next to the sizzling roasties and hot gravy. Sprinkle the reserved coriander leaves over everything and serve with any condiments you like. Life doesn’t get much better.