Place the vinegar
in a small non-reactive saucepan and heat to a boil. Add the
sugar, stirring until it has completely dissolved, then
lower the heat to medium-low and let simmer for 5 minutes.
Meanwhile, using a mortar and pestle or a bowl and the back
of a spoon, pound or mash the garlic and salt to a smooth
paste. Stir in the pepper flakes and blend well. Remove the
vinegar mixture from the heat and stir in the garlic paste.
Let cool to room temperature. Store sealed in a glass jar in
the refrigerator for up to 2 days.