Combine the olive oil, lemon juice, salt, pepper, garlic powder, paprika, and cayenne pepper in a medium bowl.
Pat the scallops dry with paper towels. Add them to the bowl and toss to coat.
Preheat a gas grill, an electric grill, or a stovetop grill pan to medium-high. Oil the grill.
Thread the scallops onto the skewers. Thread three scallops onto 2 skewers to make them easy to turn.
Grill until opaque, about 3 minutes per side.
Serve immediately, garnished with lemon and parsley.
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Notes
This recipe calls for large sea scallops. You shouldn't use small bay scallops in this recipe. They're tiny and are more suitable for stir-frying, ceviches, or salads.
Extra-virgin olive oil has the best flavor, but you can use a lighter olive oil if you prefer an oil with a higher smoke point.
If the scallops have a small, crescent-shaped muscle attached to their side, use your fingers to peel it off and remove it. It gets tough when cooked.
Scallops are done when they are golden brown, firm to the touch, and opaque. If using an instant-read thermometer, the USDA recommends an internal temperature of 145°F. America's Test Kitchen says 115°F is ideal since the temperature will continue to climb and reach 130°F.
You can keep the leftovers in an airtight container in the fridge for up to three days. Reheat them in the microwave, covered, at 50% power.