01 - Combine chicken with yogurt, lemon juice, turmeric, and salt in a large bowl. Mix thoroughly to coat all pieces. Let marinate for at least 15 minutes, up to 2 hours for enhanced flavor penetration.
02 - Heat vegetable oil in a large skillet or Dutch oven over medium heat. Add finely chopped onions and cook, stirring occasionally, until golden brown and softened, approximately 5-7 minutes.
03 - Add minced ginger, garlic, and chopped jalapeños to the pan. Sauté for 2-3 minutes until fragrant, being careful not to burn the garlic.
04 - Stir in diced tomatoes and continue cooking for 4-5 minutes until tomatoes break down and form a soft masala base.
05 - Sprinkle coriander, cumin, garam masala, cinnamon, chili powder, and black pepper over the mixture. Stir constantly for 1 minute to toast the spices and release their essential oils.
06 - Add marinated chicken pieces to the skillet. Cook, stirring frequently, for about 5 minutes until chicken develops a light golden-brown color on all sides.
07 - Pour in water or chicken broth, scraping up any browned bits from the bottom of the pan. Bring to a gentle simmer, cover, and cook for 15-20 minutes until chicken is completely cooked through and sauce reaches desired consistency.
08 - Taste the curry and adjust salt or heat level as needed. Sprinkle with fresh cilantro and serve immediately with steamed basmati rice or warm naan bread.