If the scallops are very large, cut them in half. They are cooked when they are slightly firm to the touch. I find scallops at their best when they are just barely cooked through. DRY THE SCALLOPS WITH PAPER TOWELS and set aside. Trim the leeks and discard any yellow parts. Cut the leeks at the point where they begin to turn green and discard the green parts. Split the white parts in half. Cut the white parts of the leeks at a slight diagonal into 5 cm segments. Wash them well, several times, in cold water. Heat a wok or large frying pan until it is hot, then add the oil, leeks, scallions, garlic, ginger and salt and stir-fry for 1 minute. Add the sauce ingredients and stir-fry the mixture for 3 minutes. Lastly, add the scallops and continue to stir-fry for 4 more minutes, or until the scallops are just cooked. Serve at once.