1. Remove scallops from the refrigerator, and bring them to room temperature (about 10 minutes). In a small mixing bowl, add the white onion pieces and the next 7 ingredients (through crushed red pepper); stir with a whisk to combine, and set aside.
2. Warm the canola oil in a large nonstick skillet over medium heat. When hot, add the scallops; sprinkle scallops with the black pepper. Cook scallops about 3 minutes on 1 side until golden brown. Using tongs, flip the scallops and cook 2-3 more minutes or until browned. Transfer scallops to a plate, and cover with foil. Keep the skillet on the heat.
3. Whisk the sauce again, and add it to the pan. Cook until the sauce boils and thickens slightly (about 45 seconds); then remove the pan from heat. Divide scallops among 4 plates, drizzle some of the hot sesame sauce over each portion, and garnish with a sprinkle of green onion pieces.
Look for sesame oil in the ethnic-ingredients section of your supermarket.