In a large bowl, sprinkle about half the Parmesan and half the croutons over romaine; add dressing and toss well. Place in a chilled pasta bowl or large soup plate; sprinkle with remaining Parmesan, creating a snowcap effect. Add tomato slices on one side; refrigerate. In a very well ventilated area or outdoors, heat a cast iron skillet over high heat. Brush one side of sirloin with melted margarine; sprinkle to taste with Cajun seasoning.
Place seasoned side down in skillet (Caution : there might be a slight flame when meat is placed in skillet.). While first side is cooking, brush second side with melted margarine and sprinkle with additional seasoning. Cook about 2 minutes; turn and cook 2 to 3 minutes more, or to desired degree of doneness. Cut into 1⁄2 inch slices. Fan sliced steak over salad; top with blue cheese, bacon and remaining croutons.