It’s been said there are three parts to every taco: tortilla, filling and salsa. There’s a fourth, however, and it may be the most important one: balance. It’s the balance of flavors and textures, and the ratio of filling-to-tortilla. It’s no single one of those but it’s the magic, the soul, which makes them work together. It’s not learned: it’s felt. And it’s in every taco and every dish at Tuétano Taqueria (143 West San Ysidro Blvd.).