2 tablespoons extra-virgin olive oil
1 small zucchini, finely diced
1 red bell pepper, finely diced
1 yellow bell pepper, finely diced
5 cloves garlic, smashed to a paste with coarse salt
1/2 teaspoon red pepper flakes
Kosher salt and freshly ground pepper
1 large egg, lightly beaten
1 tablespoon finely chopped fresh thyme
1/4 cup chopped fresh parsley
1 1/2 pounds ground turkey (90 percent lean)
1 cup panko (coarse Japanese breadcrumbs)
1/2 cup freshly grated Romano or Parmesan cheese
3/4 cup ketchup
1/4 cup plus 2 tablespoons balsamic vinegar