The best way to achieve the ultrathin slices of beef that are de rigueur for this sandwich is to freeze the roasted beef after cooking it, then thaw it slightly before slicing it with an electric knife.
- 1 tsp. red wine vinegar
- 3 pickled peppers, preferably sport, stemmed and thinly sliced
- 3 ribs celery, thinly sliced
- 1 small jalapeño, stemmed and thinly sliced (optional)
- 1 Tbsp. crushed red pepper flakes
- Salt and freshly ground black pepper
- 2 tsp. dried basil
- 2 tsp. dried oregano
- 3 cloves garlic, finely chopped
- 1 trimmed beef sirloin tip roast (about 2 1⁄2 lbs.)
- 6 Italian rolls, split and warmed
- Stir together the vinegar, peppers, celery, jalapeños, half the pepper flakes, and salt and pepper to taste in a bowl to make a relish. Cover and refrigerate overnight.
- Heat oven to 425°. Combine remaining pepper flakes, basil, oregano, garlic, and salt and pepper to taste in a bowl. Place roast in a roasting pan; rub with half the spice mixture. Roast for 20 minutes; reduce heat to 350° and roast for 20 minutes more. Combine remaining spice mixture with 1 quart water; add to roasting pan. Continue roasting until an instant-read thermometer inserted in the thickest part reads 130°, 20–30 minutes. Transfer roast to cutting board; let cool slightly. Skim fat from broth.
- Cut beef into thin slices. Reheat broth and beef together. Pile beef (with some of the broth) onto rolls, top with relish, and serve. For a “wet” version of the dish, dip the entire sandwich into broth before serving.