This can be a tricky recipe to get right, but the results are more than worth it for a special dinner.
Take the beef out of the fridge an hour before cooking, and rest under cover. This will help the meat to reach room temperature before cooking.
Set the oven to 200 degrees C.
First make the sauce. In a small saucepan combine the chopped shallot, peppercorns, tarragon and vinegar. Reduce by half, and then strain into a glass bowl. Place the bowl over a pan of boiling water in a bain marie, and add the egg yolk. Whisk vigorously as you add the butter, cube by cube, whisking as you go. When all the butter is incorporated, add a little more chopped tarragon and a twist of black pepper. This will stay warm in the bowl while you cook the steak.
Heat a griddle pan until very hot. Quickly sear the beef on each side, and then place in a small roasting dish. Season well at this point.
Place in the hot oven for around 10 minutes (rare) to 20 minutes (well done).
Remove from the oven, and rest for at least 10 minutes.
Slice across the grain at the table, accompanies with the warm bearnaise sauce.
Serve with fine french fries, or dauphinoise potatoes, and fresh green beans.
Please note: this recipe has been created and uploaded by a member of the Tesco Real Food online community. Tesco does not test customer recipes so cannot accept responsibility for the content, validate the results or answer queries regarding them.