Toast the sesame seeds. Place the seeds in a dry skillet over medium heat. With a spatula or wooden spoon, stir the sesame seeds until they turn golden. Be careful since the seeds will occasionally pop in the pan during toasting.
Cut peeled and pitted mango, avocado into dices. Dice tomato. And add it to a bowl.
Chop the onion and cilantro finely. Add to bowl.
Add chili flakes, sesame seeds, olive oil, balsamic vinegar, lime juice, salt and pepper.
Combine the ingredients and cover with a plastic wrap. Let it rest in the refrigerator until serving.
Notes
You can prepare this salsa in advance, but cut the avocado shortly before serving so that it doesn't turn brown.