In 5-quart casserole or bowl, combine orange juice, salt, pepper, thyme leaves, and orange peel. Add frozen chuck roast, turning to coat with orange-juice mixture. Place 2-inch-wide strip of foil over top edge of each end of meat to prevent over-cooking; cover with casserole lid or large plate. Cook at MEDIUM (50% power) 1 hour, turning roast over and replacing foil strips after 30 minutes.
Peel rutabaga and cut into 1/4-inch-thick wedges. Peel carrots and cut into 1-1/4-inch pieces.
Turn meat over again and add the vegetables. Replace foil strips; cover and continue to cook at MEDIUM 1 to 1-1/4 hours, turning meat over once more, until meat and vegetables are tender.
With slotted spoon, remove meat and vegetables from casserole to warm platter; keep warm.
Skim fat from cooking liquid in casserole. In small bowl, stir flour and water until smooth. Gradually stir flour mixture into cooking liquid in casserole. Cook at HIGH (100% power) 2 to 3 minutes, until sauce thickens, stirring every minute.
Cut meat into slices. Pour sauce into gravy boat and pass to spoon over servings.