Shrimp in Poblano Chili and Cilantro Sauce

This recipe is a shrimp version of the classic Mexican fish dish pescado en salsa poblano, or fish in poblano sauce. To make the creamy, vibrantly hued sauce that cloaks plump, gently cooked shrimp, poblano chilies, with their earthy flavor and moderate heat, are pureed with cilantro, alliums and Mexican crema, a rich cultured cream similar to but milder than sour cream. If crema isn’t available, sour cream works in its place. Serve with warmed tortillas and, if you like, rice and beans.