Chop up the lettuces into bite size pieces after rinsing and drying them well. (They really do better if you tear them - but cutting will work). Cut the onion in half from top to bottom and then laying your onion on the cut half, remove the top layer of skin. Slice the onion into very thin slices (you only need about ¼ of the whole onion for this salad). Peel the mango using a veggie peeler and then use a sharp knife to whittle small bite size pieces from the edge of the mango until you have removed all of the flesh. Mix the salad together.
Mix the Vinegar and the Olive Oil together using a whisk until it has come together. Pour over the mixed salad. Using your vegetable peeler, shave off some parmesan cheese from a block of cheese. Sprinkle with a generous amount of salt and pepper (very important to the flavor of the salad). Serve immediately.
Notes
Use other fruits instead of mango if you need to. Peach works best.