Can dried lemongrass be substituted for fresh?
Woody stalks of lemon grass, a grassy herb native to India and tropical Asia, are used in many South Asian dishes, imparting citrusy and floral flavors to soups, curries, and stir-fries. Lemon grass is also sometimes dried and sold in jars.
To test the difference between fresh and dried, we used some of each to make a curry paste (which we tasted stirred into vegetable broth), a Thai chicken soup, and a snow pea stir-fry. (Because dried herbs are more concentrated in flavor than fresh herbs, we followed our general rule by using half as much dried lemon grass as fresh in each recipe.) In all three cases, tasters found that the fresh lemon grass imparted a bright mix of citrus, floral, and minty notes, while the dried lemon grass contributed a less complex, woodsy flavor. That said, we still found the dried lemon grass to be an acceptable substitute for fresh in the paste and the soup, both of which also had a lot of other flavors contributing to the mix. But we don’t recommend the dried herb at all in stir-fries. With this dry-heat cooking method, the parched pieces of lemon grass could not hydrate and retained the texture of hay. So if you’re going to substitute dried lemon grass for fresh, make sure to use it only in recipes in which there is enough liquid for the herb to hydrate and soften.