Heat oil in a medium saucepan or wok over medium-high heat. Add onion, gingerroot and garlic. Cook while stirring for 2 minutes. Add soy, rice vinegar, apricot preserves, sesame oil and green onions. Heat to blend flavors. Taste it. Too sour? Add more preserves. Too sweet? More vinegar. Stir in green onion. Add cornstarch mixture while stirring, a little at a time, until sauce is thickened.