Remove excess moisture from the scallops and sprinkle salt and pepper on them. Coat them with flour, dip them in beaten egg, then cover them with breadcrumbs.
Heat the deep frying oil to 350°F, and deep fry the crumb-covered scallops. You can check the temperature by dropping a breadcrumb in the hot oil. If it rises to the surface immediately after being dropped, it's at the correct temperature. Fry the scallops until they turn golden brown in color and float in the oil, about 3 minutes, turning them a couple of times during frying.
Serve immediately with lemon wedges and/or optional Tonkatsu sauce for dipping.