Italian Beef Sandwiches

Prepare the Giardiniera:

1. Stir together water and salt in a large glass bowl until dissolved. Add carrots, celery, cauliflower, and fennel. Cover and refrigerate at least 8 hours or up to 12 hours.

2. Remove vegetables from brine; drain and thoroughly rinse. Stir together vinegar, oil, peppercorns, Italian seasoning, and garlic in glass bowl until combined. Stir in vegetables and olives. Divide mixture evenly among 2 pint-size jars. Cover and marinate in refrigerator at least 8 hours or up to 2 weeks.

Prepare the Italian Beef:

1. Preheat oven to 300°F. Heat oil in a large Dutch oven or heavy-bottomed pot over medium-high. Add oxtails; cook, flipping once, until golden brown, 8 to 10 minutes. Transfer to a cutting board or plate. Sprinkle roast evenly with kosher salt, black pepper, and celery salt. Add to Dutch oven, and cook, flipping occasionally, until golden brown on all sides, about 10 minutes. Transfer from Dutch oven to cutting board or plate with oxtails, and let rest for 5 to 10 minutes. Do not wipe out Dutch oven.

2. Reduce heat under Dutch oven to medium, and add onion, fennel, celery, and garlic. Cook, stirring often, until fragrant and just beginning to brown, about 5 minutes. Stir in beef stock, Italian seasoning, and crushed red pepper; return oxtails and roast to Dutch oven. Cover and cook in preheated oven until very tender, 3 hours to 3 hours, 30 minutes. Remove from oven.

3. Increase oven temperature to 325°F. Carefully transfer roast to a cutting board, and let cool, uncovered, at room temperature, about 1 hour. (Do not discard cooking liquid; it will be used as the jus.) Wrap roast in plastic wrap, and freeze for 30 minutes.

Meanwhile, prepare the Roasted Peppers:

1. Line a large rimmed baking sheet with aluminum foil. Toss together mini peppers, oil, celery salt, and black pepper. Bake at 325°F, stirring once, until tender, about 30 minutes. Remove from oven, and let cool until ready to serve.

2. Pour jus through a fine mesh strainer into a large skillet; discard solids. Bring to a simmer over medium-low, and cook, undisturbed, until heated through, about 10 minutes.

3. Remove roast from freezer, and slice as thin as possible. Add sliced meat to simmering jus; cook, undisturbed, until heated through and tender, about 10 minutes.

4. Meanwhile, coat each roll evenly with 1 tablespoon Giardiniera oil from jar, and transfer to a large rimmed baking sheet lined with aluminum foil. Bake at 325°F until dried out, about 5 minutes.

5. Divide Italian Beef evenly among 8 rolls, and top with extra jus. Top each with 1/4 cup Giardiniera and about 2 tablespoons Roasted Peppers. Serve with remaining jus. Leftover Giardiniera may be kept in refrigerator for up to 1 month.