Tip the rice into a large bowl and cover with cold water. Whisk for 1-2 mins till the water goes cloudy. Drain the rice, rinse under cold water and tip back into the bowl. Cover with fresh cold water and set aside to soak.
Place half the pot of yogurt in a mixing bowl. Peel and grate the ginger and the garlic. Add to the yogurt. Halve, de-seed and finely chop the chilli. Stir half into the yogurt (keep the rest for later). Add 1 tsp garam masala and a pinch or two of cayenne pepper (it’s spicy, so add as much or as little as you like).
Pull the leaves from the coriander stalks and set aside. Finely chop the stalks. Add to the yogurt mixture. Season with salt and pepper. Stir in the diced chicken leg. Set aside for 5 mins.
Heat your grill to medium and line the grill pan with foil. Chop the onion into chunks. Take the chicken out of the yogurt marinade, shaking off any excess. Thread the chicken and onion onto the skewers.
Place the skewers on the foil lined tray. Grill the skewers for 10-12 mins, turning once or twice, till the chicken is cooked through and beginning to char.
While the skewers grill, drain the rice. Tip into a medium pan. Add 400 ml boiling water and a pinch of salt. Cover. Bring to the boil. Turn the heat right down and simmer for 8 mins till all the water is absorbed.
To make the raita, coarsely grate half the cucumber into a bowl and stir in the remaining yogurt. Season with salt and pepper.
Add the spinach to the rice. Fork through to just wilt it. Roughly chop the coriander leaves. Serve the tandoori chicken skewers with the spinach rice and a dollop of the raita. Sprinkle over the remaining chilli and the coriander leaves to garnish.