Grilled chicken breasts with bread crust

6 slices white bread, crust removed
4 tablespoons butter, softened
1 teaspoon spicy brown mustard
2 shallots, finely diced
1 tablespoon chopped fresh herbs (parsley, chervil, chives, dill)
6 boneless, skinless chicken breasts
Salt and pepper
3 tablespoons olive oil, divided
2 portobella mushrooms, stems removed
2 large tomatoes, thickly sliced

1. In a food processor, process bread into soft, coarse crumbs. In a medium bowl, mix bread crumbs, butter, mustard, shallots, and herbs into a paste. Set aside.
2. Season chicken breasts with salt and pepper and brush with 1 tablespoon of the olive oil. Place chicken in center of cooking grate over Direct High heat and sear for 4 minutes, turning once halfway through searing time. Remove from grill just long enough to spread bread crumb paste evenly over chicken breasts. Reduce grill temperature to Medium. Place chicken on a sheet pan and bake over Direct Medium heat for about 15 minutes. Remove from grill and keep warm.
3. Season mushrooms and tomatoes with salt and pepper; brush with remaining 2 tablespoons of oil. Place in center of cooking grate. Grill mushrooms for 6 minutes and tomatoes for 2 minutes, turning once halfway through grilling time. Arrange chicken, mushrooms, and tomatoes on a platter.