Heat the oil in a frying pan (skillet) over a medium heat and fry the onion and celery until the onion is translucent, about 3 minutes. Add the lamb and fry, stirring frequently, until it browns.

Stir in the tomato puree (paste), sun-dried tomatoes, oregano, vinegar and stock. Season with salt and pepper to taste.

Bring to the boil and cook, uncovered, for 20 minutes or until the meat has absorbed the stock. Taste and adjust the seasoning if necessary.