For the giardiniera: Combine the carrots, pepperoncini, jalapeños, roasted red peppers, olive oil, pepperoncini liquid, garlic powder and pepper in a bowl. Toss well, then set aside.
For the beef: Remove the sirloin from the freezer and, using a mandoline or a sharp knife, cut into very thin strips against the grain. Sprinkle the meat with salt and pepper.
Heat the olive oil over medium-high heat in a large saute pan. Add the beef and sauté until starting to brown, but still pink, about 2 minutes. Add the Italian seasoning and garlic, then cook for 30 seconds. Add the broth and vinegar, then bring to a simmer. Remove from the heat.
Place 3 slices of provolone on each roll. Top with the hot beef. Sprinkle with some of the giardiniera. Serve with extra broth on the side for dipping.