Crock Pot Italian Beef Sandwiches

Bahan-bahan (12 porsi)

• 4 pounds beef chuck roast (or rump roast)
• 1 tablespoon vegetable oil
• 1 yellow onion (sliced)
• 1 packet Italian dressing mix (0.7 ounces)
• 16 ounces sliced pepperoncini peppers (with juice)
• 2 cups beef broth
• 1 teaspoon Italian seasoning
• 12 hoagie rolls (or 24 slider rolls)
• spicy giardiniera (or pickled vegetables for serving)