Heat the base:

Add the garlic pulp, ginger pulp, garum, water, sugar, syrup (or honey), and rice vinegar to a small saucepan. Bring to a boil.

Thicken the sauce:

Meanwhile, dissolve the cornstarch in a few tablespoons of cold water to make a smooth slurry. Reduce the heat and whisk the slurry into the pan.

Simmer briefly:

Let the sauce simmer for 1–2 minutes until it thickens.

Finish:

Remove from heat and let cool slightly before using.