Thai Soy Sauces

Soy sauce came to Thailand with Chinese immigrants, and Thai-Chinese cooking is a large part of everyday Thai food. A Thai kitchen typically has several soy sauces, and they are not interchangeable: a recipe that says “dark soy sauce” means something very different from “light”.

The main types

• Light soy sauce (si-io khao, “white soy”): thin, light brown and salty. The everyday seasoning soy for stir-fries, soups, fried rice and marinades, often used alongside fish sauce.
• Dark soy sauce (si-io dam, “black soy”): thick, almost black, slightly sweet and less salty. Used in small amounts mainly for colour and a molasses depth, as in pad see ew, khao man gai sauce and braised pork leg (khao kha moo).
• Sweet soy sauce (si-io wan): thick and syrupy, sweetened with sugar or molasses. Used in dipping sauces and for glazing, and in some noodle dishes.
• Seasoning sauce (such as Golden Mountain or Maggi): a savoury, slightly sweet soy-based sauce. Splashed into stir-fries, fried eggs and fried rice, and on rice soup at breakfast.

How to cook with them

Most Thai stir-fries combine a light soy sauce for salt, oyster sauce for body and a few drops of dark soy for colour. In noodle dishes like pad see ew, the dark soy caramelises on the wide rice noodles and gives them their characteristic colour and smoky sweetness.

Brands

Thai brands such as Healthy Boy (Dek Som Boon) make all three types and are worth seeking out; their balance differs from Chinese and Japanese soy sauces. Japanese soy (shoyu) is fine in place of light soy sauce but is a little sweeter and more aromatic.

Storing

All soy sauces keep well in a cool cupboard for months. Sweet soy sauce is best refrigerated once opened.

Cook’s tip

If you only buy one, buy light soy sauce. Add a bottle of dark soy sauce when you start making noodle dishes; a small bottle lasts a long time.