Heat a skillet over medium-high heat. Stir in the ground lamb, and cook until browned and crumbly, about 5 minutes. Drain off excess grease, and set meat aside. Heat vegetable oil in the same skillet, and stir in onion; cook and stir until the onion begins to brown, about 3 minutes. Stir in garlic, and continue cooking 1 minute more.

Stir the cooked lamb back into the skillet along with the tomato paste, curry paste, and water. Bring to a boil, then reduce heat to medium-low, cover, and simmer 15 minutes. Stir in peas, cover, and simmer 5 minutes more. Pour into a serving dish and garnish with cilantro.