Step 1

Arrange 2 racks to divide the oven into thirds and heat the oven to 450°F.

Step 2

Prepare the following, adding each to a rimmed baking sheet as you complete it: Seed and thinly slice 3 large bell peppers (about 4 cups). Thinly slice 1 medium red onion (about 2 cups). Thinly slice 4 garlic cloves.

Step 3

Add 1 pint cherry tomatoes to the baking sheet. Drizzle everything with 2 tablespoons olive oil, then sprinkle with 1 1/4 teaspoons kosher salt, 1 1/4 teaspoons dried oregano, 1/2 teaspoon black pepper, and 1/4 teaspoon red pepper flakes. Toss to coat and spread the mixture into an even layer.

Step 4

Remove the casings from 1 pound plant-based hot or sweet Italian sausages if needed. Use your hands to pinch off bite-sized pieces of the sausage and drop over the veggies.

Step 5

Roast on the lower rack, stirring halfway through, until the sausage is browned and cooked through, the peppers are tender, and the skins of the tomatoes are just starting to split, 20 to 25 minutes total. Meanwhile, thinly slice 6 large pepperoncinis (about 1/2 cup).

Step 6

Remove the baking sheet from the oven and turn on the broiler. Add the sliced pepperoncinis and 2 tablespoons pepperoncini brine to the baking sheet and toss to coat. Push the mixture to one half of the baking sheet and line the other half with aluminum foil. Place 4 hoagie rolls on the foil (do not split them open yet).

Step 7

Broil on the upper rack until the rolls are toasted, 1 to 2 minutes. Split the buns and divide the veggie and sausage mixture between them to serve.