(Nutrition information is calculated using an ingredient database and should be considered an estimate.)
For the beetroot pesto, process the beetroot, walnuts, parmesan, garlic and 1 teaspoon of the vinegar in a food processor until smooth. Season.
Preheat the oven grill to high. Line a baking tray with foil. Place the tomato, cut-side up, on tray. Drizzle with 1 tsp oil and remaining vinegar. Sprinkle with sugar. Season. Grill for 5 minutes or until blistered.
Heat a large non-stick frying pan over high heat. Drizzle the steaks with the remaining oil. Season. Cook, turning, for 1-2 minutes or until just cooked through.
Preheat a chargrill pan over medium-high heat. Spread one side of each slice of bread with Flora. Grill, Flora side-down, for 2-3 minutes or until crisp. Spread 4 slices of bread with mustard. Top with the beetroot pesto, rocket, steak, tomato and mayonnaise, if using. Sandwich with the remaining bread.