Preheat broiler or oven to 400ºF.
Place cubed tuna into a food processor and pulse it to coarsely grind the fish (it should start to look like ground beef or turkey).
Transfer tuna to a medium-size mixing bowl and add in the garlic, soy sauce, chives, some salt and freshly ground black pepper. Pat the meat down in the bowl and use the side of your hand to roughly score the mixture into four equal portions. Scoop one portion out of the bowl and divide that into four equal parts. Shape each part into a small patty and reserve on a plate. Continue dividing and shaping the remaining tuna until you have 16 patties.