2 hr 30
Heat the oil in a large frying pan over a high heat. Reduce the heat to medium-low, then sprinkle over the flour and stir to make a thick paste. Continue stirring for 15–20 minutes until the paste turns a hazelnut colour. It will be very slow to change colour, then change quickly, so watch closely so that it does not burn.
Add the onion, garlic, celery and pepper and stir for a further