Add the olive oil, thinly sliced onion, and diced tomatoes to a pan and cook over medium heat until the tomato juice is mostly cooked off.
As the tomatoes and onions are cooking, dice the jalapeño, ginger, and garlic and add to the pan. Continue cooking.
Add the turmeric, salt, cumin, coriander, and black pepper and stir to combine.
Slice the chicken into thin strips against the grain. Add the chicken, garam masala, cilantro, and water to the pan. Simmer, covered for 5-10 minutes, or until the chicken is cooked through. Serve with rice and enjoy!