Jiang you gao

Jiang you gao (醬油膏) is Taiwanese thick soy sauce, or soy paste: sweet, savoury and glossy. It is thicker than soy sauce, so it clings to food instead of soaking in. Use it where you would use oyster sauce: as a dip or drizzle (danbing, scallion pancakes, dumplings, turnip cake, zongzi) or in braises and stir-fries (lu rou fan, dan dan noodles).

Makes about 160 ml.

Ingredients

3 tablespoons light soy sauce
3 tablespoons dark soy sauce
4 tablespoons water (or shiitake or kombu soaking water for extra umami)
2 tablespoons mirin
3 tablespoons coconut sugar (or brown sugar)
2 teaspoons Chinese black vinegar (aged balsamic works in a pinch)
1/8 teaspoon garlic granules (skip when making the garlic version)
1/8 teaspoon coarse sea salt
1 small pinch five spice powder
1 tablespoon glutinous rice flour (optional, see below)
2 tablespoons cold water (only if using the flour)

Garlic version (蒜蓉醬油膏)

2 cloves garlic (~10 g), finely minced
1 teaspoon neutral oil

Directions

add everything except the glutinous rice flour and the cold water to a medium pot
bring to a low simmer over medium-low heat, stirring until the sugar has dissolved (5 to 6 minutes), do not let it boil hard
in a small bowl, stir the glutinous rice flour with the cold water until smooth (cold, so it doesn’t clump)
whisk the slurry into the pot
keep stirring for about 2 minutes, until the sauce is a bit thinner than maple syrup and coats the back of a spoon
turn off the heat and let it cool, it thickens a little more as it cools
if it ends up too thick, stir in a splash of water; if too thin, add a bit more slurry or simmer a little longer

Garlic version

first fry the garlic in the oil on low heat until fragrant, without browning
add the remaining ingredients (without the garlic granules) and continue as above
alternatively, stir the minced raw garlic into the finished sauce for a sharper flavour

Without glutinous rice flour

Use a common starch instead: cornstarch, potato starch or tapioca starch. Sweet potato starch also works, but is darker and less clear.

replace the 1 tablespoon glutinous rice flour with 2 teaspoons cornstarch (or potato or tapioca starch), mixed with the same 2 tablespoons cold water
whisk the slurry into the simmering sauce and cook for only 30 to 60 seconds, until it thickens, then take it off the heat
it thickens more as it cools, so stop while it is still a bit thinner than you want
add more slurry in small amounts if it ends up too thin
these starches are less stable than glutinous rice flour: after a few days in the fridge the sauce can turn jelly-like or release water, stir it or warm it up briefly before use

Without any starch, simmer the sauce for 10 to 15 minutes until it is syrupy and reduced by about a third. Watch it closely at the end, the sugar can burn. The result is thinner and less clingy.

Notes

keeps up to 5 days in an airtight container in the fridge, stir before using
can be frozen in ice cube trays for up to 6 months, thaw in the fridge or melt in a pan
if it sets too firmly in the fridge, microwave for 10 seconds on medium power, stir, and add a splash of water if needed
to make it gluten-free, use gluten-free soy sauces and mirin