1. Preheat grill to medium-high heat. In a large bowl, mix ground beef with onion and 1 tbsp hot sauce. Shape into 4 patties. Grill patties for about 10 min., flipping once.
2. While burgers cook, make the sauce. In a small bowl, combine the remaining 2 tbsp hot sauce, blue cheese dressing, and crumbled blue cheese. In the last 2 min. while the burgers finish cooking, toast buns cut side down on the edges of grill. Spread cut side of each bun with blue cheese dressing. Serve hamburgers in buns.
Per serving: 422 calories, 21g fat, 8g saturated fat, 80mg cholesterol, 616mg sodium, 28g carbohydrate, 1g fiber, 7g sugar, 28g protein