Step 1

Preheat the oven to 220C/425F/Gas 7 (fan 200C).

Step 2

Rub the fillet of beef with plenty of salt and pepper and the oil.

Step 3

Heat a large frying pan until very hot. Fry the fillet on all sides until browned. Transfer to a roasting tin.

Step 4

Place the fillet in the centre of the roasting tin, arrange the whole garlic bulbs around the fillet and drizzle with a little oil. Roast for 23 minutes for medium-rare (only 20 minutes if it is a long, thin piece).

Step 5

When the beef is cooked, remove from the oven, cover with aluminium foil and leave to rest for 15 minutes.

Step 6

Serve hot or you can leave it to cool, and then wrap in more foil and place in the fridge to cool completely.

Step 7

To make the sauce, cut the roasted garlic bulbs in half horizontally and squeeze the garlic paste from each single clove into a bowl. Add the mayonnaise, crème fraîche and sugar.

Step 8

Blend to a smooth purée using a blender or food processor. Stir in the wholegrain mustard. Chill until ready to serve alongside the beef.

Step 9

Carve the beef into thin slices just before serving.