Hello Richard, this is a very common issue when dealing with frozen scallops, so please do not be discouraged. Most packaged frozen scallops are what the industry calls wet scallops, meaning they have been treated with a sodium phosphate solution that causes them to absorb and hold excess water. When they hit heat, all that trapped moisture releases instantly and boils the seafood.
Here is a step by step approach to get that restaurant-quality golden crust tonight.
First, make sure they are fully thawed. The best method is placing them on a plate lined with multiple layers of paper towels in your refrigerator for several hours or overnight. If you are short on time today, place them in a sealed ziplock bag and submerge the bag in a bowl of cold tap water for about 20 to 30 minutes. Avoid using warm water or the microwave, as that will begin cooking the delicate meat.
Second, inspect each scallop and gently pull off the small rectangular side muscle if it is still attached. It is completely edible, but it tends to be tough and chewy.
Third, drying the surface is the absolute most critical step. Line a baking sheet with several layers of dry paper towels, lay the thawed scallops flat, and press more paper towels firmly on top. If you have 30 to 45 minutes to spare, leave them uncovered on fresh paper towels inside your refrigerator. The cold circulating air will dry the exterior surfaces significantly, which is essential for browning.
Fourth, season with salt and freshly cracked black pepper right before they go into the pan. If you salt them too early, the salt will draw out interior moisture and make the surface wet again.
Finally, the cooking technique. Place a heavy stainless steel or cast iron skillet over medium-high heat until it is properly hot. Add a high-smoke-point cooking oil, such as avocado or grapeseed oil, just enough to coat the bottom. Place the scallops into the pan with at least an inch of space between each one. Do not crowd the pan, as crowded scallops will trap steam.
Once they are in the pan, resist the urge to move them. Let them sear undisturbed for about 90 seconds to 2 minutes until a deep golden crust forms on the bottom. Flip them gently, add a small knob of cold butter if you like for flavor, and sear the other side for only 1 to 2 minutes. They should be just opaque and slightly springy to the touch. Transfer them immediately to a warm serving plate to rest for a minute so they do not overcook in the residual pan heat.
I hope this helps you achieve a wonderful family dinner tonight. Please let me know how they turn out.