In a pan, heat oil over medium-high heat. Add chopped onions and cook until translucent, about 4 minutes. Stir in minced ginger and garlic, cooking until fragrant.
Add ground chicken and salt, then stir-fry for 5 minutes, or until fully cooked. Make sure to break the meat into small pieces.
Lower the heat to medium. Mix in cumin, coriander, turmeric, red chili powder, and diced tomatoes. Cook for 5 minutes.
Add ¾ cup of water and cover the pan. Let it cook for about 2 minutes.
Add bell peppers and green chilies, then stir to combine. Cover and simmer for about 8 minutes, until the bell peppers are tender but still crunchy. If the sauce is too watery, bring it to a simmer uncovered until it reduces to your desired consistency.
Turn off the heat and stir in garam masala, cilantro, and lemon juice. Taste and add salt as needed.
