Add oil to a large pan and set over medium-high heat. When oil is hot, put in the ginger, garlic and curry leaves (they may spit if they're fresh). Stir. When garlic just starts to brown, add the meat. Stir one or twice and turn heat to medium low.
Add the garam masala, cumin, turmeric, cayenne pepper, green chili and salt. Stir. Add 3/4 cup water, cover pan and cook gently for 50 minutes before uncovering and boiling down the liquid. Stir in lots of freshly ground black pepper and lemon juice.