Peel the mango and then cut the yellow flesh away from the stone in the center. Dice the mango flesh finely and add it to a large mixing bowl together with the chopped red onion. Slice the cherry tomatoes in half and deseed them. Slice or dice the tomatoes finely and also add them to the mixing bowl.
Stir the salsa well again. Check the taste and add extra salt, chili powder or lemon juice to taste if necessary. Cover the bowl. Let the salsa marinate at room temperature for at least 30 minutes so the flavor can develop. Stir regularly. Transfer the salsa to a large bowl and serve with crackers.