Vietnamese Tuna Burger

Name: Vietnamese Tuna Burger
Ingredients: 1/2 tablespoon seasoned rice vinegar; 1 tablespoon plus 1 teaspoon sesame oil, divided; 1/2 tablespoon plus 1/4 teaspoon brown sugar, divided; 1 cup shredded red cabbage; 1/2 cup shredded carrots; 1/2 cup broccoli slaw; 1/2 cup chopped fresh cilantro; 1/4 cup chopped fresh mint; 1 tablespoon plus 1 teaspoon fish sauce; 1 tablespoon plus 1 teaspoon light soy sauce; 1 1/4 pound tuna steak, finely chopped; 1/2 cup sliced scallions; 1/2 cup panko breadcrumbs; 4 hamburger buns, split