Combine the yogurt with the salt, spices, garlic, and ginger in a bowl, and mix well. Add the chicken thighs and make sure that the chicken is coated well in the yogurt marinade. Let it rest overnight, or 1 hour at least, in the fridge.
Heat the oil in a pan. Add the cumin seeds and bay leaf. Once they start to sizzle, add the onions and cook for 15 minutes, until a lovely golden color. Now add the tomatoes and cook for 10 minutes, until softened. Add the spices and salt, and cook for 1 minute. Add the marinated chicken, mix well, and cover. Cook for 40 to 45 minutes over low heat until the chicken is cooked through.
Once you have cooked the curry, let it rest for 30 minutes to 1 hour. This makes the curry really intense and the chicken soaks up the flavors better. Sprinkle with some coriander and serve.