Make the dressing first by placing all dressing ingredients except EVOO into Thermomix bowl and mixing 10 sec/speed 6. Add oil and stir through for 4 sec/speed 6. Drizzle over rocket leaves and set aside.
Make the burger patties, without cleaning the Thermomix bowl. Place cheese into Thermomix bowl and grate for 2 sec/speed 6. Set aside.
Place walnuts, peppercorns and salt into Thermomix bowl and mill for 6 sec/speed 7.
Add umami paste, beef mince, sauce and grated cheese to Thermomix bowl and combine for 10 sec/Reverse + speed 7 with the aid of the spatula.
Form into 6-8 equal burger patties, place onto baking paper and refrigerate until ready to cook.
Assemble burgers; Char grill buns and patties to taste. Cook bacon. Spread mayonnaise on bottom half of bun, add cooked burger patty, top with slice of tomato, dressed rocket leaves and a slice each of bacon and cheese. Drizzle with additional dressing or mayonnaise if desired.
Serve immediately.