Trim fat from meat. Make a lengthwise cut down the center of the meat, cutting to within 1/2 inch of the other side. Spread meat open.
In a small bowl combine rosemary, garlic, salt, fennel seeds, and pepper; mash slightly with the back of a spoon. Spread garlic mixture over meat. Roll meat into a spiral, starting from a short side. Tie with heavy 100-percent-cotton kitchen string. Transfer meat to a baking dish; cover and chill for 24 to 48 hours.
At least 30 minutes before cooking, soak wood chips in enough water to cover. Drain before using. Remove meat from refrigerator 30 minutes before grilling.
For a charcoal grill, arrange medium-hot coals around a drip pan. Test for medium heat above pan. Sprinkle drained wood chips over coals. Remove meat from baking dish. Place meat on grill rack over drip pan. Cover and grill for 2 hours. Carefully remove meat from grill. Double wrap meat in heavy foil; return to grill. Cover and grill for 1 3/4 to 2 hours more or until meat is very tender. Add more coals during grilling as needed to maintain temperature and smoke. (For a gas grill, preheat grill. Reduce heat to medium. Adjust for indirect cooking. Add wood chips according to the manufacturer's directions. Place meat on a rack in a roasting pan; place pan on grill rack over burner that is off. Grill as above.)
Carefully remove meat from foil packet and place on a cutting board or platter, reserving the hot juices. Let meat stand for 15 minutes. Using two forks, pull meat apart into shreds.
To serve, cut each loaf of Homemade Focaccia into eight slices. Top eight of the slices with shredded meat and arugula. If using, thin Berry Mostarda with some of the meat juices if necessary to reach spreading consistency. Spread the remaining eight focaccia slices with mustard; place, spread sides down, on top of meat.
In a large mixing bowl combine 2 1/2 cups of the flour, the yeast, 2 teaspoons salt and sugar. Add warm water and 1/4 cup oil. Beat with an electric mixer on low speed for 30 seconds, scraping sides of bowl constantly. Beat on high speed for 3 minutes. Using a wooden spoon, stir in cornmeal and as much of the remaining flour as you can. On a lightly floured surface, knead in enough of the remaining flour until a soft dough just forms (2 to 3 minutes). Transfer to a very large oiled bowl, turning once to oil surface. Cover bowl and refrigerate 6 to 24 hours. Bake until golden, 12 to 15 minutes. Remove bread from pans and cool completely on wire racks. When cool, cut each into 8 equal pieces.
Oil two 15x10x1-inch baking pans. Turn dough out onto a lightly floured surface and divide into two portions. Roll and stretch dough to fill the two prepared pan. Cover and let rise in a warm place until nearly double in size (45 to 60 minutes).
Preheat oven to 450 degrees F. Lightly oil fingers and make indentations in dough; brush focaccia lightly with oil and sprinkle with the 1 teaspoon salt.
Bake until golden, 12 to 15 minutes. Remove bread from pans and cool completely on wire racks. When cool, cut each into 8 equal pieces.