For sauce, sauté mushrooms over high heat in 2 tablespoon of butter until limp. Add wine to pan and scrape up any pan drippings. Add broth, thyme, vinegar and pepper; bring to boil. Melt remaining 3 tablespoons of butter and blend with flour. Stir flour/butter mixture into sauce and cook, stirring until thickened. Keep warm.
Grill or broil steak as desired. Drop Mann’s Broccolini® into saucepan of boiling water. Cook for 3 minutes, drain. Serve Broccolini® and steak with sauce. Makes 2 ⅓ cups sauce.