1 cup coarsely chopped cauliflower florets
1⁄2 cup extra-virgin olive oil
1⁄2 tsp. dried oregano
1⁄2 tsp. dried thyme
1 small carrot, thinly sliced crosswise
1 small rib celery, thinly sliced crosswise
3⁄4 cup chopped pitted oil-cured green olives
1⁄4 cup chopped pitted oil-cured black olives
2 tbsp. chopped drained pimientos
Salt and freshly ground black pepper, to taste
1 tbsp. chopped flat-leaf parsley leaves
1 8" round loaf Italian bread, preferably with sesame seeds, halved
6 oz. sliced mortadella
6 oz. sliced provolone
6 oz. sliced soppressata
1. Put the cauliflower, oil, oregano, thyme, carrots, celery, and 3 tbsp. water into a small pot. Bring to a boil over medium-high heat, then reduce heat to medium-low. Simmer, covered, until vegetables are just tender, 10–12 minutes. Transfer contents of pot to a small bowl, then stir in olives, pimientos, and salt and pepper. Let relish cool. Stir in parsley; set aside.
2. Using your hands, hollow out insides of each bread half. Brush inside of top half with some of the oil from the relish. Fill bottom half with relish; press down. Layer mortadella, provolone, and soppressata over relish, being careful not to let cheese or meat hang over the sides of the bread. Cover with top half of the bread and tightly wrap sandwich with cling film. Place sandwich on a tray; weigh down with a couple of heavy objects, such as a cast-iron skillet topped with a small pot. Refrigerate for 2–3 hours. When ready to serve, remove plastic wrap and cut sandwich into quarters.