Step 1. Pat shrimp completely dry with paper towels. Season lightly with salt. If your shrimp are large (21-25 count), consider butterflying them open lengthwise so they cook evenly and absorb more flavor.
Step 2. In a large skillet or cast iron pan, warm the olive oil over medium-low heat for about 1 minute until shimmering but not smoking. Add the sliced garlic immediately — this is crucial because starting with warm oil prevents burning.
Step 3. Cook the garlic gently for 4-5 minutes, stirring frequently, until it turns a light golden color. Watch carefully: if it starts to brown at the edges, reduce heat and remove the pan from heat briefly. You're looking for fragrant, golden slices, not dark or bitter ones.
Step 4. Increase heat to medium-high and add shrimp in a single layer (cook in batches if necessary — don't crowd the pan). Let them sear undisturbed for about 1 minute until the bottoms turn pink.
Step 5. Flip each shrimp, sprinkle with red pepper flakes, and cook another 30-60 seconds until opaque and just cooked through. Internal temperature should reach 120°F (49°C). Shrimp are done when they form a loose "C" shape — if they curl tightly into an "O," they're overcooked.
Step 6. Remove pan from heat immediately. Add sherry and lemon juice, scraping up any browned bits from the bottom of the pan. The liquid will sizzle and reduce slightly. Taste and adjust seasoning with additional salt or pepper.
Step 7. Transfer shrimp to a shallow serving dish, ladle the hot garlic oil over them, and sprinkle generously with chopped parsley. Serve immediately while still bubbling in the pan.
