In a small bowl, add green onions, ginger, garlic, cilantro, rice vinegar, sesame oil, soy sauce, 2 tbsp of canola oil, and the lime juice. Whisk ingredients together. Reserve.
Remove the tough muscle from the side of each scallop if this has not already been done. Do not rinse scallops — their natural juices will help the sesame seeds stick. Season with salt and pepper. Place sesame seeds on a plate. Pat down top and bottom sides of each scallop in sesame seeds. Reserve on a plate.
On a sauté pan, over medium-high heat, add remaining tbsp canola oil. When oil is hot, add scallops, placing them sesame-crusted-side down. Sear for approximately 1-1/2 minutes, or until the sesame seeds on the bottom turn golden brown. To help maintain the bond between the seeds and the pan, avoid moving the pan. Turn and sear on other sesame-crusted side for 1 minute.
To assemble, line up Asian-style soup spoons for each bite. Place one tsp of vinaigrette in each spoon, and top with a scallop.