Preheat oven to 250 degrees.
Add the tuna to a large mixing bowl. Break up the pieces a bit with a fork.
Add the eggs to the bowl, whisking with the fork. Add the remainder of the ingredients, stirring well with a spoon until combined.
Heat a mini waffle iron. When ready, add 1/4 cup of the tuna waffle batter to the waffle iron. Close and cook for approximately 3-4 minutes, until cooked through. Repeat for all the waffles.
Place all the waffles on a baking sheet(s) in a single layer. Place in the preheated oven for 5 minutes (this helps them all warm back up evenly and crisp up).
Meanwhile, prepare the topping, combining the tomatoes, avocado, and balsamic vinegar (if using).
When waffles are ready, serve immediately with the topping.