Spoon 2 tbsp of the yogurt into a dish. Peel and grate the ginger and garlic. Halve the chilli, flicking out the seeds for less heat. Finely chop it. Finely chop the coriander stalks (save the leaves for later).
Add the grated ginger, garlic, chilli and coriander stalks to the yogurt. Measure out 1 tsp each of the garam masala and smoked paprika and stir into the yogurt mix. Add the chicken to the dish. Turn to coat in the yogurt. Set aside for 10 mins.
Heat your oven to 200°C/Fan 180°C/Gas 6. Peel and finely dice the onion. Tip the rice into a bowl and cover with plenty of cold water. Whisk for 1-2 mins so the water goes cloudy. Drain.
Grease a baking tray with 2 tsp oil. Place the coated chicken on the tray and roast for 25 mins till golden brown and cooked through. (Insert a skewer into the chicken to check it’s done – the juices should run clear and the meat should be white.)
While the chicken cooks, warm a small pan over a medium heat. Add 1 tsp oil and the onion. Season. Fry for 5 mins, stirring now and then, till the onion is soft. Add the rice. Pour in 350 ml boiling water. Cover. Bring to the boil. Turn the heat down and simmer for 6-8 mins till all the water is absorbed.
While the rice cooks, grate half the cucumber. Stir it into the remaining yogurt with some seasoning. This is your raita. Set aside.
Take the rice off the heat. Set aside, lid on, for 2 mins to finish cooking. Fork the spinach into the rice to just wilt. Slice the chicken and serve with the rice, garnished with the coriander leaves. Sprinkle a little smoked paprika over the raita and serve on the side.