A quick turn on the grill brings out the natural sweetness of bell peppers. Here, they're tossed with cherry tomatoes, capers, red-wine vinegar, olive oil to top crostini.
Heat grill to medium-high. Place peppers skin side up on grill, cover, and cook until beginning to soften, 5 minutes. Turn peppers over and cook until charred, about 4 minutes. Remove from grill and let cool.
Cut peppers into thin strips. In a medium bowl, combine peppers, tomatoes, capers, vinegar, and oil. Season with salt and pepper. Top bread with pepper mixture and Parmesan.