Black salt, also known as kala namak, is a sulfurous salt that gives a distinctly eggy flavor. You can find it in Indian grocery stores or u003ca href=u0022https://silkroadspices.ca/products/kala-namaku0022 target=u0022_blanku0022 rel=u0022noreferrer noopeneru0022u003eonlineu003c/au003e. If unavailable, you can substitute with regular salt, though the salad will taste less eggy.