Add the sliced shallot, Greek yogurt, sour cream, heavy cream, white wine vinegar, chopped dill, salt, white pepper, and powdered sugar. Stir to combine.
1 small shallot, 150 g Greek yogurt, 100 g sour cream, 50 ml heavy whipping cream, 2 tablespoon white wine vinegar, 2 tablespoon fresh dill, ¾ teaspoon salt, ⅛ teaspoon white pepper, ½ teaspoon powdered sugar