Slow roast beef with fines herbes pesto

Preheat the oven to 100°C.

Turn the beef tail underneath to achieve a fillet of even thickness.

Tie the beef at intervals to ensure it retains a neat shape while cooking.

Sit the fillet in a shallow roasting dish.

Mix the mustard and tarragon together and spread evenly over the fillet.

Roast in the preheated oven for 2 hours.

When the beef is cooked, remove from the oven and allow to rest, covered, for at least 15 minutes before carving, though the beef can be set aside and served when ready.

Serve with cream-loaded potato gratin and seasonal vegetables, with the fines herbes pesto on the side for guests to serve themselves.

Boil the potatoes in plenty of water with salt, bay leaf, and garlic until almost cooked. Drain well.

To the saucepan add the cream, crème friache and nutmeg or mace.

Bring to scalding point, transfer to a large well-greased oven proof dish and scatter over the cheese.

Bake at 180°C for 20 minutes until hot and golden.

For best results, bake this a day or two ahead; cool, cover chill and reheat 30 minutes before required.

Process all the ingredients except the oil in a food processor.

With the motor still running, slowly pour the oil down the feed tube to make a thick paste.

Season with salt and a squeeze of lemon juice if wished.