Step 1

Cut 1/2 head cauliflower into bite-sized florets (about 2 1/2 cups). Peel 2 medium carrots and thinly slice crosswise on a slight diagonal (about 1 cup). Thinly slice 2 medium celery stalks crosswise on a slight diagonal (about 1 1/4 cups). Cut 1 medium red bell pepper into 1/4-inch-thick strips (about 1 1/2 cups).

Step 2

Place 2 cups white wine vinegar, 1 cup water, 1 tablespoon plus 1 1/2 teaspoons kosher salt, 1 tablespoon granulated sugar, and 2 bay leaves in a medium saucepan and bring to a boil over medium-high heat. Reduce the heat to maintain a simmer, add the cauliflower and carrots, and simmer for 3 minutes. Add the celery and red bell pepper, and simmer until all the vegetables are crisp-tender, about 2 minutes more. Remove the saucepan from the heat.

Step 3

Add 16 whole pickled peperoncini and stir to combine. Cover and let sit for 5 minutes. Meanwhile, place 1/4 cup extra-virgin olive oil, 2 teaspoons fennel seeds, and 1 teaspoon dried oregano in a large bowl.

Step 4

Transfer 2 tablespoons of the liquid in the saucepan to the bowl and whisk until combined to make the marinade. Drain the vegetables, then add them to the marinade. Toss well to combine. Let cool until room temperature, about 20 minutes.

Step 5

Cover (or transfer to an airtight container) and refrigerate for at least 1 hour and up to 1 day. Serve cold or at room temperature. Toss again before serving.