In a large oven-friendly bowl break up tuna and add mayonnaise until the tuna becomes completely coated.
Cream the avocado in a small bowl until smooth and add to tuna.
Finely chop rest of vegetables and add.
Throw in a pinch of salt and pepper and sprinkle cheese on top. You can either pop it in the oven on broil for a few minutes or mix it up for a quick snack.