This burger has some of the same flavors as a popular sushi roll. Be sure to process the tuna using quick pulses to prevent the meat from being overworked and overheated by the blade.
How to Make It
Preheat grill to medium-high heat.
Combine first 3 ingredients in a small bowl. Cover and chill.
Dissolve 1/4 teaspoon sugar in 3 tablespoons vinegar in a medium bowl, stirring with a whisk. Add cucumber and red onion; toss to coat. Cover and chill.
Place tuna in a food processor; pulse until finely chopped. Combine chopped tuna, green onions, next 3 ingredients (through salt), 1 1/2 tablespoons vinegar, and 3/4 teaspoon sugar in a bowl. Divide mixture into 6 equal portions with moist hands, shaping each into a 1/2-inch-thick patty. Press thumb in center of patty, leaving a nickel-sized indentation.
Place patties on grill rack coated with cooking spray; grill 4 minutes. Turn patties over; grill 4 minutes or until desired degree of doneness. Remove from grill; cover and let stand 5 minutes.
Spread 1 tablespoon mayonnaise mixture evenly on cut sides of each bun. Top bottom halves of buns with patties. Spoon cucumber mixture evenly on top of patties, using a slotted spoon. Arrange cilantro evenly over cucumber mixture. Cover with bun tops. Serve immediately.
Cooking Light, Crave!