In a chilled mixing bowl, add all ingredients except for watermelon radish, shiso and extravirgin olive oil. Fold ingredients together, season with salt and pepper, and then divide into 6 equal portions on 6 plates. Drizzle each plate with aioli, then pack each portion of tartare (chopped meat) into a ring mold and place in the center of each plate. Toss the watermelon radish with the shiso and place on top of the tartare and drizzle with the extra-virgin olive oil. Serve with crostini or toasted baguettes.
Whole-Grain Mustard Aioli
Combine all ingredients in food processor and mix until smooth. Put in a squeeze bottle and store in the refrigerator up to 1 week.