Christopher Kimball goes on a fishing trip off the Pacific Coast of Mexico to learn the art of Mexican seafood. Back at Milk Street, he prepares Slow-Cooked Snapper with Chili and Lime, inspired by pescado zarandeado. Then, Matthew Card prepares aguachile negro, or Mexican-Style Shrimp in Chili-Lime Sauce. Rosemary Gill gives a lesson on Chilis 101 and we visit Santiago Muñoz at his tortilleria Maizajo to learn the secret to amazing heirloom tortillas.