Pat the shrimp dry with paper towels and season with salt and pepper. Zest the lemon, then juice it, keeping zest and juice separate.
Heat 2 tablespoons of the olive oil in a 12-inch skillet over medium-high heat until it shimmers. Add the shrimp in a single layer, working in two batches so they don't touch. Sear 1 to 2 minutes per side, until pink on the outside but not fully cooked through. Transfer to a plate.
Lower the heat to medium and add the remaining 1 tablespoon olive oil. Add the garlic and red pepper flakes, and cook for 30 seconds, until fragrant.
Add the cherry tomatoes, cut side down, and cook for 3 to 4 minutes, until they start to soften and release some juice.
Pour in the white wine and lemon juice, scraping up any browned bits from the bottom of the pan. Simmer for 2 minutes, until slightly reduced.
Return the shrimp and any juices to the skillet. Cook for 2 to 3 minutes, stirring occasionally, until the shrimp are fully opaque and curl into a loose C shape, or until an instant-read thermometer reads 145 F / 63 C.
Remove the skillet from the heat. Scatter the feta and lemon zest over the top, cover, and let sit for 2 minutes so the feta softens slightly.
Stir in the butter until it melts into the sauce, then sprinkle with oregano or parsley. Serve right away, straight from the skillet.