Step 1

FOR THE SAUCE: Whisk all ingredients in bowl until combined; set aside.

Step 2

FOR THE SHRIMP: Whisk flour, water, eggs, ½ teaspoon salt, and ¼ teaspoon pepper in bowl until no lumps remain. Spread panko in shallow dish..

Step 3

Combine granulated garlic, cayenne, remaining ¾ teaspoon salt, and remaining ¼ teaspoon pepper in small bowl. Pat shrimp dry with paper towels and sprinkle with spice mixture.

Step 4

Working with 1 shrimp at a time, hold shrimp by tail and dip into batter, letting excess drip back into bowl, then coat with panko, pressing gently to adhere. Arrange breaded shrimp on rimmed baking sheet. Refrigerate while heating oil (breaded shrimp can be refrigerated for up to 2 hours).

Step 5

Line platter with triple layer of paper towels. Add oil to large Dutch oven until it measures about 1 inch deep and heat over medium-high heat to 350 degrees. Add one-third of shrimp, one at a time, to hot oil. Fry, stirring gently to prevent shrimp from sticking together, until shrimp are golden brown, 1 to 2 minutes after adding last shrimp.

Step 6

Transfer shrimp to prepared platter. Return oil to 350 degrees and repeat with remaining shrimp in 2 more batches. Serve immediately with sauce.

Step 7

TO MAKE AHEAD: At end of step 4, freeze breaded shrimp on sheet until firm, then transfer to zipper-lock bag and freeze for up to 1 month. Do not thaw before cooking; increase cooking time by 1 to 2 minutes.