What is the difference between tom yum and tom kha?
Tom yum is a hot-sour soup that is often served clear, though there is also a popular creamy version (tom yum nam khon). Tom kha includes coconut milk and is richer and more mellow, with galangal and lime still doing their thing.
Can I make this without galangal?
Yes. Galangal is piney and peppery, but ginger is a good substitute. Use the same amount of sliced fresh ginger. The soup will still be delicious, just a bit less distinctly tom yum.
Do I have to use makrut lime leaves?
They are a major part of the signature aroma. If you cannot find them, use wide strips of lime zest (avoid the white pith) plus an extra squeeze of lime at the end. It will not be identical, but it will be bright and tasty.
Is tom yum supposed to be super spicy?
It can be, but it does not have to be. Start with a smaller amount of chili paste, taste, then add more. The goal is a balanced punch, not a soup that makes you see your ancestors.
Can I make this vegetarian?
Absolutely. Use vegetable stock, swap fish sauce for vegan fish sauce (best option), and use tofu or extra mushrooms. If you do not have vegan fish sauce, use soy sauce plus a pinch of salt to taste and a tiny bit of seaweed (kombu) or mushroom powder for that deeper, ocean-y umami.
What mushrooms work best?
Straw mushrooms are classic. In most grocery stores, cremini or white button mushrooms work great. Slice them thick so they stay meaty.