Heat the oil in a large pan over medium heat until shimmering.

Sauté the minced garlic, chopped green chili, and chopped ginger in the hot oil for about 1 minute until fragrant.

Add the diced onion and cook until golden brown, about 3-4 minutes.

Stir in the spices: turmeric, chili powder, ground cumin, ground coriander, and garam masala. Cook for another minute.

Add chopped tomatoes and water, season with salt, and bring to a boil for about 5 minutes.

Reduce heat to low and simmer uncovered for about 10-15 minutes until the sauce thickens.

Add chicken thighs to the sauce, cover, and cook for about 20 minutes until tender.

Squeeze lemon juice over the dish and garnish with chopped coriander before serving warm.