Originally Posted by CWS4322
My understanding is that citric acid = sour salt. Lemon/lime salt is not citric acid. It is called "sour salt" because it looks like table salt, not because it is a combination of salt + lemon/lime. Given the origins of "sour salt" and the region the cookbook represents, I'm guessing the N.A. equivalent is food-grade citric acid. Maybe I've misunderstood?
No, you haven't misunderstood. Sour salt = citric acid.
Citric acid sold in a dry powdered form is commonly sold in markets and groceries as "sour salt", due to its physical resemblance to table salt. It has use in culinary applications where an acid is needed for either its chemical properties or for its sour flavor, but a dry ingredient is needed and additional flavors are unwanted (e.g., instead of vinegar or lemon juice).