MARINATE CHICKEN: Make the masala paste. Cut the chicken into bite size pieces. Marinate with 1 tablespoon of masala paste and the yoghurt for about 30 minutes in the fridge.
COOK: Heat a large, deep skillet over medium high heat and add the remaining masala paste. Stir fry for a few minutes to get all the spices going. Add the chicken/yoghurt mixture and sauté until the chicken is mostly cooked.
SIMMER: Add the tomato purée and coconut milk to the pan with the chicken and simmer for 15 or so minutes. Season with salt. Let stand for a while so the sauce will thicken up a bit.