Pour 1 qt. water into a deep pot. Add salt and warm over high heat, stirring, until salt dissolves. Remove from heat and stir in 2 qts. cold water, garlic, ground chiles, and oregano. Nest pan in ice water until cool. Stir in remaining ingredients.
Accompaniments
Corn or flour tortillas
Cilantro sprigs
Lime wedges
Chopped white onion