Remove any tough stems from dill and discard. If desired, reserve a few fronds of dill for garnish, then aggressively chop the rest of the dill fronds until they are very finely chopped and almost turn into a paste. Measure 1/4 cup (this should be about all of it) and place in medium bowl.

If desired, reserve a few chives for garnish, then aggressively chop the rest of the chives until they also turn into a very finely chopped almost-paste. Measure 2 tablespoons (this should be about all of it) and add to bowl with dill.

Add yogurt, mayonnaise, Parmesan, lemon juice, horseradish, salt, pepper, Tabasco and sugar to bowl and whisk until well combined.

Refrigerate at least 4 hours or overnight before serving, garnished with chopped reserved dill and chives, and grated lemon zest, if desired.