Place the potatoes and water in a microwave-safe dish; microwave on high until almost tender, about 7-9 minutes. Set aside (do not drain).
In a 3-qt. microwave-safe dish, cook beef and onion on medium until beef is browned, about 8 minutes; drain. Add potatoes and remaining ingredients. Cover and microwave on medium for 12 minutes or until potatoes are tender and vegetables are heated through.