Heat the oil in a large wok or frying pan. Add the onion and celery and cook for 5 minutes until softened. Add the garlic, paprika, cayenne pepper and tomato purée, and cook for 1 minute, stirring. Add the pork, peppers and stock, and cook for a further 2 minutes.
Meanwhile, cook the rice to pack instructions. Add to the pan, heat gently and cook, covered, for 2-3 minutes until the stock has been absorbed. Remove from the heat and leave to stand for 5 minutes. Sprinkle over the extra paprika and serve with the lemon wedges.