- In a large skillet, cook onion in hot, melted butter over med heat until tender.
- Add in mushrooms and garlic; cook about 5 minutes or until mushrooms are tender, stirring occasionally.
- Transfer mixture to a greased 3-quart baking dish.
- Stir in the water, barley, dry soup mix, thyme, and salt.
- Bake, covered, at 350° for about 1 hour and 15 minutes or until barley is tender and most of the liquid is absorbed, stirring once or twice.
- Let stand, covered, for 15 minutes before serving.