Thursday salt is a dark salt produced in the Kostroma region, Russia. It is associated with Russian Orthodox Easter traditions, and was historically produced at the Trinity Lavra of St. Sergius monastery on Maundy Thursday.[1] [2]
The salt is created by mixing rock salt with flavourings such as kvass, herbs, or rye, and baking the mixture at a very high temperature for several hours. The process reduces the sodium chloride content and increases the content of other minerals such as calcium and potassium.