Cook pasta: In a pot of salted boiling water, cook the pasta according to the directions on the package, once cooked drain completely and run under cold water to cool.
Prep ingredients for the macaroni salad per instruction above.
Make macaroni salad: In a bowl, mix together all of the ingredients. Taste and adjust the seasoning with salt and pepper or more mayo if needed. Refrigerate until you are ready to serve.
Make meat filling: In a nonstick pan over medium heat, cook the beef until no longer pink and drain the grease. Stir in the ketchup, water, Worcestershire sauce, mustard, garlic powder, and season with salt and pepper. Bring to a simmer until the sauce is well combined and thickened.
Lightly toast the roll.
Assemble: Spoon the meat filling on the bread.
Serve: Enjoy the sloppy joe with macaroni salad, pickles, and sparkling water.