1In 10-inch skillet, cook beef over medium-high heat, stirring occasionally, until thoroughly cooked; drain.
2Stir in uncooked Pasta, Sauce Mix, milk, hot water, the steak sauce and mushrooms. Heat to boiling, stirring occasionally. Reduce heat; cover and simmer 10 minutes, stirring occasionally, until pasta is tender. Remove from heat.
3Top with onions. Cover; let stand about 5 minutes or until sauce is as thick as you'd like (sauce will thicken as it stands).