Clean, wash and cut the leek into rings. Heat the oil in a large pan. Fry the minced meat in it until crumbly. Season well with salt and pepper. Stir in tomato paste, sweat briefly. Add leek and fry for about 5 minutes. Season everything with salt and pepper.
Put the minced leek mixture into an ovenproof dish. Whisk eggs, milk and mustard. Pour egg milk over the minced meat mixture. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 45 minutes. Take out and arrange on plates. Put a dash of crème fraîche on each piece. Serve with boiled potatoes and salad
With 6 people: