Place all the burger ingredients in a mixing bowl and stir to combine. Using your hands, shape into four equal-sized patties. Preheat the grill to hot. Brush the burgers with a little oil. Cook the burgers under the grill for 10- 12 minutes, turning over half way through. Before serving mix the horseradish sauce into the mayonnaise. Place the baps under the grill just briefly to toast about 2 minutes. Spread the bottom halves of the baps with the mayonnaise mixture and some rocket leaves, followed by the sliced tomato and then finally the cooked burger.
See more Beef recipes
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.