Preheat the oven to 400°F.
Peel a large potato, cut them into 1-inch dice and put them into a pan of cold salted water. Bring to the boil, simmer for a few minutes, drain and allow to steam in a colander.
Put a heaped teaspoon of turmeric into a bowl and add the zest of 1 lemon, half a teaspoon of ground cumin, 5 sprigs of chopped fresh cilantro, a quarter of a red pepper, roughly chopped and a 1-inch piece of fresh ginger, peeled and finely sliced into matchsticks.
Cut 3 slices off the lemon and set aside. Squeeze the juice from the remainder of the lemon into the bowl.
Shake the potatoes up in the colander and add them to the bowl with 1 chicken breast, skin left on. Toss everything around with a splash of olive oil and season well with sea salt and freshly ground black pepper.
Remove the chicken, put the potatoes into the pan in one layer, and top with the lemon slices and the chicken. Drizzle with olive oil and cook in the middle of the oven for 25 to 35 minutes.