1/2 tsp dried chili flakes or cayenne
2 cloves garlic, coarsely chopped
1 tblsp brown sugar
1/4 tsp salt
1/2 cup chinese red rice vinegar
a thinly sliced green onion
1 tblsp coarsely chopped cilantro leaves

Pound first 4 ingredients to a paste with mortar and pestle, then dissolve in vinegar. Alternatively, put it all in a blender and blend until smooth. Float the green onions and cilantro on top.