Carefully place the Large Egg (6) in a medium saucepan and cover with water by 1 inch. Bring to a boil over high heat. Once simmering, remove the pan from the heat and let the eggs stand until cool enough to touch.
Meanwhile, place the Red Potato (2 pound) in a large saucepan or stockpot and cover with well-salted cold water by 2 inches. Bring to a boil and simmer until the potatoes are fork tender, about 15 minutes. Drain well and transfer to a large mixing bowl.
Peel the eggs and add to the potatoes. Using a masher or fork, crush the eggs until the whites and yolks are broken up, and the potatoes are still fairly chunky.
Stir in the Radish (1/2 cup), Mayonnaise (1/3 cup), Dijon Mustard (1/4 cup), Capers (2 tablespoon), Fresh Chives (2 tablespoon), and Tarragon (2 tablespoon). Taste for seasoning and add more Sea Salt (to taste) if necessary.
Transfer to a serving bowl and garnish with additional herbs, sprouts, or dollops of Radish Leaf (to taste) pesto.