How can I cook tom yum soup? Can I replace lemon grass with somethingelse as we do not have it where I live?

'geomark' is right. Another option is using Tom Yum chili paste which's already mixed essential ingredients, suggested brand -- Mae Ploy, Mae Sri. You can easily find them in any asian supermarket in china town. It can be kept for long time in the fridge. Enjoy your Tom Yum :)

NO. You can not substitute anything for lemon grass. You can simply make the salty and sour taste in the soup (and the spicyness from chillies of course) by using fish sauce and lemon juice but without the lemon grass, you will NEVER get that authentic aroma. Sorry. cateaway is correct... you can use pre-made tom yum paste or "stock cubes" - which should be readily available in the asain food section of any decent supermarket. It can be just as good. But if you want to use REAL fresh ingredient - then, there is NOTHING that you can use to substitute lemongrass. Cheers from Australia

Please let us know where are you are from so we can tell you what you have in your country that you can use as a substitute!