Cut chicken into pieces, and season with a little salt and pepper. Set aside.
In a large bowl, combine the sour cream or plain yogurt with the lemon juice, tumeric, garam masala, chili powder, cumin, ginger paste, minced garlic, and toss with chunked up chicken.
Cover and refrigerate at least 1 hour. Preferably longer.
Heat the vegetable oil and butter over high heat in a large fry pan.
Add the chicken coated in the Marinade and cook for 3-4 minutes. Flipping once.
Add the pureed tomato, sugar and salt. Stir to combine.
Turn down to low and cover with lid. Let simmer for 20 minutes if using chicken thighs, 15 minutes if using chicken breasts.
Add the cream, and stir well.
Garnish with cilantro leaves.
Serve over rice and enjoy!