Preheat oven to 425°F. Slice bun tops into 1/4-in. strips (if bun tops are very thick, slice bottoms off horizontally before slicing into strips). Arrange in a single layer on Large Bar Pan; bake 8-10 minutes or until lightly toasted. Remove to Stackable Cooling Rack; cool completely.
Cut onion in half crosswise using Utility Knife. Slice half of the onion crosswise into thin rings using Ultimate Mandoline fitted with thin slicing blade. Cut tomatoes into quarters lengthwise and slice crosswise. Set onion and tomatoes aside.
Cook ground beef in (8-in.) Sauté Pan over medium-high heat 5-7 minutes or until no longer pink, breaking beef into crumbles using Slotted Turner. Chop remaining onion half using Food Chopper. Finely dice pickles using Utility Knife. In Classic Batter Bowl, combine chopped onion, pickles, ketchup and mustard. Add cooked ground beef; mix well using Small Mix 'N Scraper(R).
To serve, arrange lettuce on large serving platter. Spoon beef mixture over lettuce. Top with cheese, tomatoes and sliced onion. Arrange hamburger bun croutons around edge of platter. Serve immediately.
Yield: 6 servings
Nutrients per serving: Calories 250, Total Fat 10 g, Saturated Fat 5 g, Cholesterol 55 mg, Carbohydrate 20 g, Protein 19 g, Sodium 750 mg, Fiber 2 g