Heat the oven to Gas 4, 180°C, 350°F. Top and tail the beetroot and cut into wedges. Put in a bowl and add ½ tablespoon olive oil then toss well to coat all over. Place in the oven and roast for 30 minutes or until soft when a knife is inserted.
Mix together the vinegar, caster sugar and English mustard until smooth. In a small jam jar add the olive oil and water, screw on a lid and shake until blended.
Heat the grill to high and cook the steaks to your liking, rare 2 minutes on each side, medium 3-4 minutes each side and well done 5 minutes each side.
Remove and place on a carving board, allow to rest for 2 minutes. Divide roasted beetroot between four plates, and scatter with mixed salad leaves. Slice the steak into ribbons and top each salad with half a prepared steak. Spoon over a fine drizzle of the mustard sauce and serve.
Watch our video on how to cook a steak.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.