Spray on the vinegar.
Ask chefs the easiest way to improve food, and chances are they'll say to use more acid. Vinegar, lemon juice – anything tart keeps flavors from feeling flat and balances saltiness, sweetness, or fattiness. But Michael Voltaggio of Ink.Sak has a problem with pouring on vinegar: "When the bread gets wet, it's like it's eating itself from the inside!" So he uses one of those mini spray bottles from a drugstore to spritz vinegar onto his sandwiches, delivering flavor without sogginess.