Chop the cherry tomatoes up and them add them to a mixing bowl together with the chopped onion, a pinch of garlic powder, pepper and salt, the ground cumin, lime juice and half of the freshly chopped cilantro and mint.
Stir well until you get a chunky tomato salad. Then check the seasoning. Add extra pepper, salt, cumin, lime juice or garlic powder to taste if necessary. Place the tomatoes in the fridge to chill. In another bowl combine the drained tuna, the black beans and the rest of the freshly chopped cilantro and mint. Season with some pepper and salt.