Slice the onion into rings and the radish thinly. Marinate both with lime juice.
Make the fennel ‘slaw’; thinly cut or grind the fennel and the apple and mix with a spoonful of mayonnaise and finely chopped fennel greens. Season with salt and pepper. Mix the remaining mayonnaise with finely chopped tarragon.
Toast the bun halves on a (grill)pan. Generously spread the beet spread on the buns. Place the beet leaf lettuce and tarragon mayonnaise on top.
Cook Garden Gourmet’s Sensational Burgers in a frying pan according to the instructions on the package.
Top the burgers with fennel slaw, red onions, radish and rocket. Spoon tomato ketchup and extra tarragon mayonnaise on top and place the bun lid.