The trick to this sauté is to brown, not burn, the halved cloves of garlic so they impart a pleasant, nutty flavor. Peperoncini, the small, dried chiles native to Calabria, add sweet heat if you have some in the pantry; conventional crushed red pepper flakes work just fine, too. Serve with a loaf of rustic bread and a green salad.
Warm a large heavy-based skillet over medium-high heat for 1 minute.
Add the oil and garlic and once the garlic starts to sizzle steadily, add the shrimp, spacing them evenly in the pan. Cook, undisturbed, until the shrimp brown around the edges and easily release when you lift one, 2 to 3 minutes.
Flip the shrimp, sprinkle the thyme and pepperoncino around the pan, and cook until the shrimp become firm to the touch and opaque. Remove the shrimp from the pan and set aside.
Add the sliced lemon to the pan and sauté for 1 minute.
Transfer the lemon to a platter, then top with the shrimp. Serve immediately.