Dissolve salt and sugar n 1 quart cold water in a large container. Submerge shrimp, cover, and refrigerate for 15 minutes. Remove shrimp from brine and pat dry with paper towels.

Heat 1 tablespoon oil in a 12-inch skillet over high heat until shimmering. Add shrimp shells and cook, stirring frequently, until they begin to turn spotty brown and skillet starts to brown, 2 to 4 minutes. Off heat, carefully add wine and thyme sprigs. When bubbling subsides. return skillet to med um heat and simmer gently, stirring occasionally, for 5 minutes. Strain mixture through colander set over large bowl. Discard shells and reserve liquid (you should have

about ⅔ cup). Wipe skillet clean with paper towels.

Combine lemon juice and cornstarch in a small bowl and set aside. Heat remaining 1 tablespoon oil, garlic, pepper flakes, and pepper in now-empty skillet over medium-low heat, stirring occasionally, until garlic Is fragrant and just beginning to brown at edges, 3 to 5 minutes. Add reserved wine mixture, increase heat to high, and bring to simmer. Reduce heat to medium, add shrimp, cover, and cook, stirring occa­sionally, until shrimp are just opaque, 5 to 7 minutes. Remove skillet from heat and, using a slotted spoon, transfer shrimp to bowl.

Return skillet to medium heat, add lemon juice/cornstarch mixture and cook until slightly thickened, 1 minute. Off heat, whisk in butter and parsley until combined. Return shrimp and any accumulated juices to skillet and toss to combing. Serve, passing lemon wedges separately.