Heat the oil in a flameproof casserole dish or large frying pan over a medium heat. Add the onion and a generous pinch of salt and fry for 8-10 mins, or until the onion has turned golden brown and sticky. Add the garlic and ginger, cooking for a further minute.
Chop the chicken into chunky 3cm pieces, add to the pan and fry for 5 mins before stirring through the spice paste and tomatoes, along with 250ml water. Bring to the boil, lower to a simmer and cook on a gentle heat uncovered for 25-30 mins or until rich and slightly reduced. Stir though the yogurt, coriander and ground almonds, season and serve with warm naan or fluffy basmati rice.