Whirl 1/2 cup lemon juice, mustard, ginger, brown sugar, and 1/2 tsp. each salt and pepper in a blender until smooth.
Pour in oil with motor running. Whirl in parsley, then chill sauce in a small bowl.
Boil 4 cups water, wine, 1/4 cup lemon juice, and 1 tsp. each salt and pepper in a large pot. Add shrimp; cover, remove from heat, and let steep just until shrimp are opaque, 3 to 4 minutes. Drain; immerse in ice water until cold. Serve with sauce.
Top Wine Picks:
Elk Cove 2009 Pinot Blanc (Willamette Valley; $19). Fresh grapefruit and white peach aromatic jasmine and Meyer lemon zest.
The Four Graces 2010 Pinot Blanc (Willamette Valley; $20). Exotic riot of spiced peaches, Asian pear, pink grapefruit, gardenia, and wet stones.
La Rochelle 2009 Pinot Blanc (Arroyo Seco; $24). Delicate and flamboyant at once, with lemon-lime, a core of white peach, touch of green apple, and light honeysuckle.