Mix cornstarch, soy sauce and water. In a large nonstick skillet, heat 2 teaspoons oil over medium-high heat; stir-fry scallops until firm and opaque, 1-2 minutes. Remove from pan., In same pan, heat remaining oil over medium-high heat; stir-fry snow peas, leeks and ginger until peas are just crisp-tender, 4-6 minutes. Stir cornstarch mixture; add to pan. Cook and stir until sauce is thickened, about 1 minute. Add scallops; heat through. Serve with rice.