1. Fill medium bowl with ice water; set aside. Combine 2 cups water, wine, and next 4 ingredients in medium saucepan. Bring to boil. Add shrimp; reduce heat to low, cover, and poach just until shells are pink and shrimp are opaque in center, 3 to 4 minutes. 2. Using slotted spoon, transfer shrimp to bowl with ice water; reserve poaching liquid and lemon half. Drain and peel shrimp, leaving tails intact. Devein shrimp.

3. Squeeze juice from reserved lemon half into poaching liquid in pan. Boil liquid until reduced to generous 2 tablespoons, about 20 minutes. Strain; cool.

4. Mix sour cream or crème fraîche, chopped chives, horseradish, lemon peel, and 1 tablespoon reduced poaching liquid in small bowl. Season sauce with coarse salt and black pepper.

4. Spoon dipping sauce into short glasses. Arrange shrimp on rims. Garnish with whole fresh chives and extra lemon peel if you have it.