Combine soy sauce and next 4 ingredients in a heavy-duty zip-top plastic bag; add scallops. Seal and marinate in refrigerator 30 minutes, turning occasionally.
Remove scallops from bag, reserving marinade. Slowly stir cornstarch into marinade with a whisk. Add enough water to marinade mixture to measure 2/3 cup.
Heat 1 teaspoon olive oil in a large nonstick skillet over medium-high heat. Add 1/2 of scallops and cook 3 to 4 minutes on each side or until golden. Remove scallops from pan; set aside and keep warm. Repeat procedure with remaining oil and scallops.
Transfer scallops to serving plates. Wipe pan with a paper towel. Reduce heat to medium-low. Stir marinade mixture and pour into pan; bring to a boil, stirring constantly. Reduce heat, and simmer 1 minute or until slightly thick, stirring occasionally. Pour mixture over scallops; top with cilantro and sesame seeds. Garnish with lime wedges, if desired.