Combine tuna with mayonnaise, garlic, salt and pepper. Add carrot, sweet potato, zucchini, green onion, corn and flour; stir to combine. In a separate bowl, whip egg whites until stiff; gently fold into the tuna mixture.
Heat half the oil in a large, non-stick skillet set over MEDIUM HEAT. In batches, drop 1/3 cup portions of the batter into the skillet; flatten slightly with the spatula. Cook for 4-5 minutes per side or until golden and set. Repeat with remaining batter, adding more oil as needed. Hold batches in a warm oven until all the fritters are cooked.