Preheat oven to 325°F. Mix sugar and cinnamon in a large bowl.
Whisk egg white until foamy. Add almonds; toss. Add almonds to sugar mixture; toss. Spread on a baking sheet in a single layer. Bake for 20 minutes, turning once.
In a bowl, mix blue cheese, mayonnaise, vinegar, salt and pepper.
Warm oil in a skillet over medium-high heat. Season steak with salt and pepper. Cook, turning once, 5 minutes for medium-rare. Transfer to a cutting board.
Place lettuce in a large bowl. Toss with 1/2 cup nuts and dressing. (Reserve extra nuts for another use.) Top with onion and tomato. Cut steak into thin slices, arrange on salad and serve with dressing.