Heat oven to 325°F; season roast with salt and pepper.
Heat oil in a covered Dutch oven over medium-high; brown roast 4 minutes per broad side.
Add broth and Worcestershire; stir oregano, garlic powder, onion powder, and red pepper around beef.
Cover; roast 70 to 90 minutes, turning once, until center reaches 145°F.
Transfer to a board; rest 15 minutes. Freeze 30 minutes until firm, not frozen.
Slice as thinly as possible across grain with a sharp slicing knife.
Skim excess fat from jus; return slices. Gently warm 5 to 8 minutes until saturated and at least 165°F, without boiling tough.
Split rolls, leaving hinges intact. Fill each with hot beef and 2 tablespoons jus.
Top each with 2 tablespoons giardiniera; serve extra strained jus for dipping.