The perilla leaf is a herbaceous leaf that's consumed in Korea, Japan, and some parts of Thailand and Vietnam. In Korea and Japan, it's used in various side dishes and entrees because of their fresh herbal flavor. The underside of the perilla leaf can be purple or green with thin veins running along the stem to the outer edges. Korean perilla leaves are slightly different from Japanese shiso leaves. Korean perilla leaves are larger, with smoother edges, and are slightly more stiff so can be marinated, pickled, and used in kimchi. Japanese shiso leaves are thinner, more delicate, and have jagged edges. Both have similar flavors but the shiso leaf has a stronger mint flavor in my opinion.