Himalayan black salt was once used as medicine in India. Now it's becoming a staple among vegans.

It takes a full day working in temperatures up to 1,000 degrees Celsius to make one batch of Himalayan black salt, or kala namak. The salt was once used as a medicine to treat indigestion. Today, it's a staple in South Asian cuisine, and it's known for its unique eggy and umami taste. But the long and dangerous process of making it has pushed people away from the craft.