Peel and chop the onion. Wash the meat, dab dry and cut into bite-sized pieces. Heat oil in a pot. Brown the meat all around. Add 1 teaspoon curry paste and fry briefly. Remove the meat.
Sauté the onion and lentils in the frying fat. Deglaze with 1 litre water, bring to the boil, add 1 teaspoon of paste. Simmer for 15-18 minutes. Clean, wash and cut leek into rings. After 10 minutes of cooking time add leek and meat, finish cooking. Stir in stock and season with salt and pepper