Hello Susanne,
We actually did a lot of testing of lemon grass substitutes earlier this year and, unfortunately, did not find any of them to be worth purchasing. There are many sources online that suggest using lemon zest if you can't find fresh lemon grass. One source says that it is the closest common ingredient to lemon grass but the fragrance will not be as intense and complex. They say to use about ½ teaspoon lemon zest for each stalk of lemon grass.
Below is the testing information that ran in the July-August issue of our magazine.
Taste Test: For Lemon Grass, Accept No Substitutes
The fresh lemon grass available in the U.S. tends to be old, fibrous and woody, which is why we peel away the outer layers and even then usually discard the stalks after they have simmered in our cooking liquid. So we wondered whether any of the alternatives available at most grocery stores—including dried, powdered and pastes—were a better choice.
They were not. We tested nine of them in steamed rice and found all of them lacking. Though the dried stalks had the best aroma, flavor was muted or unpleasant. Tasters described Wise Wife dried lemon grass as having a citronella candle flavor and Pride of India as acrid and bitter. Also, the dried stalks typically come in small pieces that are more complicated to steep and strain.
The powdered options offered little or no flavor. Worse, Spice Way powdered lemon grass actually gave the rice a greasy texture. Meanwhile, the pastes had a sour, tinny flavor from citric acid or other preservatives, and they often contained other ingredients that muddied their flavor, including sugar, lime juice and oil.
So fresh—even when it isn’t the freshest—really is best. When shopping for lemon grass, look for stalks with a firm texture, good fragrance and supple leaves. Opt for the heaviest, most bulbous stalks; older ones become lighter as they lose moisture. And use the scratch-and-sniff test: Gently scratch the base with a fingernail to see how much fragrance is released.
To use fresh lemon grass, trim the base and the upper part of the stalk so only 4 to 6 inches of the bottom remain, then remove any dry outer leaves. Be sure to also bruise the stalks to release their essential oils. A meat mallet or rolling pin works well.
