Steak sandwich with horseradish mayo

Place the steak between plastic wrap and flatten with a meat mallet.

Season steak with salt, pepper, finely sliced garlic and a little olive oil.

Heat a heavy-based frying pan, then cook steak for 1 minute on each side. Set aside on a plate to rest.

Brush cut surfaces of rolls with olive oil, toast under the grill, then rub with cut side of the remaining garlic clove. Spread a generous amount of horseradish mayo on the bottom half of each roll. Top with a piece of steak and then some watercress. Cover with the top half of the roll and serve.

To make the horseradish mayo, in a blender, whiz all ingredients except the oil and horseradish until well mixed. With the motor running, slowly add the oil in a thin stream, until the mayo thickens. Stir in the horseradish.