Heat oil in a pan and sauté the diced onions for 3 minutes.
Add Patak's Madras paste and sauté for another 2 minutes.
Add chopped tomatoes and let it simmer for 5 minutes.
Add diced chicken and simmer for 15-20 minutes, adding water if the sauce is too thick.
Add yogurt, salt, and chopped coriander.
Simmer for another 5 minutes until the chicken is tender and cooked through.
Serve hot, ideally with raita and naan.
