I’ve been getting lots of emails asking whether it’s okay to use ginger in Tom Yam or Tom Kha when galangal, fresh or frozen, cannot be found. The short, blunt answer is: no, it’s not. The more diplomatic, gosh-there-are-so-many-toes-in-this-world-and-I-don’t-want-to-step-on-any answer is: it depends.
If someone wants to make a new soup that is inspired by, and vaguely reminiscent of, these two dishes, by all means, they should be free to use ginger (or any roots and rhizomes for that matter) and have fun in the kitchen. If they and their loved ones enjoy the end result, that’s an even bigger reward right there, and they should be proud of their culinary creativity and the new soup that perhaps deserves a name of its own.
But if they want to replicate these two iconic Thai soups as they are made in contemporary Thai cuisine (there are historical documents showing that galangal wasn’t always used in Tom Yam), my opinion is that they cannot use ginger and expect to achieve their goal. This is especially true when it comes to Tom Kha for what would Tom Kha be without the kha (galangal)?
This is not food snobbery; this is me telling you that no cook worth his or her salt will ever tell you that ginger can be used in place of galangal (or vice versa) in a recipe. The two may look similar, but they don’t taste the same. To paraphrase one of my readers’ comment (thanks, Ian!) on my Facebook wall, ginger and galangal are as interchangeable as parsley and cilantro. That is to say, they are not interchangeable at all.
So what should one do in the complete and utter absence of fresh, frozen, or brined galangal?
Short of growing your own herbs, traveling to large coastal cities where fresh Asian ingredients are available 24/7, or paying a lot of money to have some online grocers overnight them to you, the remedy is commercial Tom Kha and Tom Yam pastes. They’re made for a situation like this.
The flavors of the herbs have already been incorporated into these pastes. Some brands of Tom Kha paste even have spray-dried coconut milk in them so you can just dissolve the paste into plain water and get a coconut-based soup (albeit severely anemic — I’d use coconut milk). Most brands already include fish sauce and lime juice in the paste, so you can just add the meat. More fish sauce, lime juice, or chilies can be added to taste.
If you can’t find galangal, but have some lemongrass lying around, by all means, slice some up and reinforce the lemongrass essence in the paste with fresh lemongrass. No galangal or lemongrass? Do you have some frozen kaffir lime leaves? How about bruising up a couple and throwing them into the pot? Many Thai restaurants overseas, who face the same problem as you, do this all the time (and aren’t they the places where many of you have met and fallen in love with these soups?).
Sure, these pastes come with MSG and some preservatives. So it’s up to those with zero tolerance for these things to decide what works best for them: ginger-flavored non-Tom Yam/non-Tom Kha, Tom Yam and Tom Kha made with these pastes, or no Tom Yam or Tom Kha.
As I said above: this is not food snobbery. This is about finding a solution that makes the most sense in a less-than-ideal situation. Commercial Tom Yam and Tom Kha pastes are my proposed solution.