Combine first 5 ingredients; stir well. Set aside.
Coat a wok or large nonstick skillet with cooking spray; heat at medium-high (375°) until hot. Add scallops; stir-fry 5 to 7 minutes or until scallops are opaque. Remove from wok, and set aside. Add broccoli, carrot, and garlic; stir-fry 5 to 7 minutes or until crisp-tender. Add snow peas; stir-fry 1 minute. Return scallops to wok. Stir cornstarch mixture well with a wire whisk, and add to wok. Cook, stirring constantly, 3 minutes or until thickened and bubbly. Sprinkle with cashews, and serve over rice.