The term 'Sour Brew' can be summarized as a type of beverage made by fermenting a mixture of grains, hops, and yeast. The crossword solution for this term is 'alegar, ' which is a type of sour beer brewed in the Basque region of Spain. It is made with a combination of barley, wheat, and rye, and is fermented with wild yeast. Alegar has a tart, acidic flavor and is often served with a slice of lemon or lime.