Cook the fava beans in water and salt. Boil the corn just in plain water (do not add salt). Use a large bowl to combine onions, fava beans, corn, tomato, parsley, oregano and aji Amarillo. Queso fresco and olives should wait until the end.
For the dressing: mix vinegar, olive oil, key lime juice, salt and pepper. Mix the veggies with the dressing, and at the end (on each plate), topped with diced olives and queso fresco.