Cook couscous according to package directions on the range top, except omit margarine or butter and salt.
For sauce, stir together preserves, soy sauce, gingerroot, and crushed red pepper; set aside. thinly slice steak on the bias into bite-size strips.
Place beef strips in a 1.5-quart casserole. Cover and micro-cook on 100% power (high) for 5 or 6 minutes. (low-wattage ovens: 8 to 9 minutes) or till meat is tender, stirring after 3 minutes. Remove meat and discard juices.
In the casserole place mushrooms, green and red pepper strips, and green onions. Pour sauce mixture over the vegetables. Toss gently till mixed. Cover and micro-cook on high for 4 to 5 minutes (low wattage ovens: 7 to 8 minutes) or till pepper strips are crisp-tender, stirring after every minute.
Stir together vinegar and cornstarch, then add mixture to casserole. Stir in meat. Micro-cook, uncovered, on high for 3 to 4 minutes (low wattage ovens: 5 to 6 minutes) or till mixture is thick and bubbly, stirring after every minute. Serve with cooked couscous or rice.