Soak cellophane noodles in hot water for 10 minutes, until tender. Strain and set aside.
While the noodles are soaking, in a small bowl, whisk together soy sauce, garlic, vinegar, sugar, sesame oil, cornstarch, and red pepper flakes. Set aside.
Heat olive oil in a large skillet over medium-high heat. Add scallops and season the tops with black pepper. Cook 2 minutes, until golden brown. Flip with spatula and cook 2 more minutes, until second side is golden brown. Add soy sauce mixture to pan and bring to a simmer, for 2 minutes, until sauce thickens and scallops are cooked through and have an opaque color.
Serve half of the scallops over all of the cellophane noodles and top with scallions. Reserve remaining scallops for salad, if desired.