Pat scallops dry with a dish towel or paper towels. It’s very important to get out as much of the liquid as possible.
Drizzle or brush scallops with olive oil on both sides and season with salt and pepper. Place back in the refrigerator until the grill is ready (it’s important to keep scallops cold for as long as possible).
Preheat an outdoor grill or indoor grill pan over medium-high heat. Rub the grates liberally with an oil with a high smoke point (such as canola or vegetable oil) to prevent the scallops from sticking. Place the scallops directly onto the grates and grill for 2-3 minutes per side, or until slightly charred on the outside and completely opaque.
Sea scallops work best for grilling, so I do not recommend substituting with bay scallops. Sea scallops are up to three times larger in size than bay scallops, so you can put them directly on the grill (without fear that they will fall through the cracks).
Scallops can be labeled as either "wet" or "dry." When at all possible, it's best to purchase "dry" scallops. A wet scallop has been soaked in a preservative phosphate solution, which makes the scallop absorb more water. When you cook a wet scallop, it tends to shrivel up more and doesn't brown as well. The wet scallops also don't taste quite as fresh. By contrast, a dry scallop is not treated with any chemical additives or solutions.
Make sure that you dry the scallops really well with a dish towel or paper towels. This helps them brown on the outside, while still staying moist and tender on the inside.
You can tell that the scallops are done when they are opaque. This only takes a few minutes on each side, so keep a close eye on them and be careful not to overcook the scallops (or they will turn out tough and rubbery).
You can use fresh or frozen scallops. If starting with frozen sea scallops, I prefer to thaw them before grilling.
To thaw Scallops: Leave the frozen scallops in the refrigerator overnight. If short on time, place the frozen scallops in a bowl of cold water for about 15-25 minutes. Take them out of the cold water and gently pat them dry and absorb all the liquid before seasoning and grilling.
To sear the scallops instead of grilling them, follow the preparation instructions, but instead of placing the scallops on a grill, place them in a very hot skillet with 1 tablespoon oil. Make sure the skillet is really hot, and be sure to use an oil with a high smoke point (like canola oil or vegetable oil). Sear the scallops for about 2 minutes on the first side, then flip them over, add a pat of butter to the pan (for flavor), and continue cooking for about 2-3 more minutes. They should be golden brown on both sides.