In a screw-top jar, combine the oil, vinegar, mustard, tarragon, and salt. Cover; shake well. Set aside.
Slash fat on edges of steak at 1-inch intervals. Place steak on the unheated rack of a broiler pan. Broil 3 to 4 inches from the heat to desired doneness, turning once. Allow 10 to 12 minutes for medium rare (145 degree F), 12 to 15 minutes for medium (160 degree F). Cut the meat into 1-inch cubes.
In a large mixing bowl, combine the beef, cauliflower, broccoli, peppers, onion, and bacon. Toss to mix well.
Shake the dressing; pour it over the beef mixture. Toss to coat. Arrange on a dinner plate over lettuce. Sprinkle with Parmesan. Makes 4 servings.