1. Prepare rice mix according to package directions.
2. Meanwhile, melt butter in a large skillet over medium-high heat; add onion, and sauté 7 minutes or until golden. Add mushrooms and salt; sauté 4 to 5 minutes or until mushrooms are tender. Add Marsala, and sauté 3 minutes or until liquid is absorbed. Stir mushroom mixture and parsley into prepared rice.