Adapted from Food.com
Make the meatballs: In a large bowl, combine the chicken, egg, bread crumbs, tomato paste, salt, pepper, garam masala, and cilantro until well incorporated then shape into balls.
Heat a large pan over medium high heat adding a small amount of oil then once hot, sear the meatballs on at least two side, about 6-7 minutes then remove from the pan once browned and set aside on a plate (they do not need to be cooked through at this point).
Make the sauce: In the same pan, still over the heat, add a little more oil if needed then add the onion, garlic, and peppers and cook until softened, about 3 to 5 minutes.
Stir in the spices, and tomato paste and cook through for 2 minutes before adding the canned tomatoes and bringing to a simmer.
Turn the heat to the lowest setting and mix in the coconut milk or heavy cream and add the meatballs into the sauce simmering for 20-30 minutes until the meatballs are cooked through and the sauce has thicken.