Siciliano Burger With Fresh Ciliegine and Sweet Tomato

3/4 cup sun-dried tomatoes packed in olive oil
2 tablespoons oil from sun-dried tomatoes
1 teaspoon mild honey
1/2 cup red flame seedless grapes (substitute green grapes, if necessary)
2 tablespoons (plus 1 teaspoon) brine-packed capers, rinsed and drained
1/2 cup fresh flat-leaf parsley, chopped
freshly ground black pepper
1 pound ground veal
3/4 pound ground beef
4 cloves garlic, minced
1/2 cup fresh Italian bread crumbs
1/4 cup pine nuts
1 teaspoon ground cinnamon
large pinch of ground cayenne
1 teaspoon dried rosemary, ground in spice grinder
1 teaspoon kosher salt (or more to taste)
freshly ground black pepper
6 Ciliegine (1/3 ounce fresh mozzarella cheese balls)
vegetable oil, for brushing on the grill rack
12 leaves radicchio, trimmed to fit the bread
oil from sun-dried tomatoes, for brushing on the radicchio
6 pieces Italian bread (3 x 4 inch), preferably rosemary bread, halved lengthwise


Preheat a gas grill to medium-high heat.
To make the tomato butter, combine the tomatoes, oil, honey and grapes in a food processor and process to a paste.  Transfer to a bowl and stir in the capers and parsley. Season the tomato butter with salt and pepper to taste and set aside.

To make the patties, combine the veal, beef, garlic, bread crumbs, nuts, cinnamon, cayenne and rosemary in a large bowl and season with salt and pepper.  Handling the meat as little as possible to avoid compacting it, mix well.  Divide the mixture into 6 equal portions and flatten into 6 disks.
Place 1 ciliegine in the center of each disk, then bring up the meat to enclose the cheese in the middle. Form into 6 patties to fit the bread sections.

When the grill is nice and hot, brush the grill rack with vegetable oil. Place the patties on the rack, cover and cook, turning once, until done to preference, 5 to 7 minutes on each side for medium.
Meanwhile, brush the radicchio lightly with tomato oil and grill until charred but still crisp, about 4 minutes.
During the last few minutes of cooking, place the bread, cut side down, on the outer edges of the grill rack to toast lightly.
To assemble the burgers, spread the tomato butter over the cut sides of the bread. On each bread bottom, place a radicchio leaf, a patty and another radicchio leaf.  Add the bread tops and serve.