Heat oil in a nonstick pan over high heat. Add onion and salt; cook and stir until onion has softened, about 5 minutes.
Reduce heat to low; stir in garlic and ginger until fragrant. Add hot water; cover, and cook, stirring occasionally, until water has evaporated, about 5 minutes.
Add chili powder, ground coriander, cumin, and turmeric; cook and stir over high heat until spices are toasted, about 5 minutes. Stir in tomatoes and green chiles; cover and cook over low heat for 5 minutes.
Add chicken; cook and stir over high heat until browned, 5 to 7 minutes. Stir in curry paste; reduce heat to low, cover and cook until chicken is cooked through, adding a little water if necessary, about 5 minutes. Check seasoning and sprinkle with freshly chopped cilantro.