This two-ingredient chicken marinade is seriously mad genius. Feta does double duty here, as its salty brine creates an easy marinade and its cheese makes a delicious sandwich spread when whipped with lemon juice and olive oil. (Seriously, this whipped feta is the perfect mayo substitute.) This tasty chicken sandwich comes together with chewy ciabatta bread, crunchy veggies, and sweet piquillo peppers, but the juicy, subtly tangy chicken is what really takes this dish to the next level.