Peel the garlic and the ginger. Cut of the tops of the chilies and discard. Chop the ginger, garlic and chilies.
Place the sugar in a thick-bottomed pot. Add the chopped garlic, chilies and ginger, and the salt.
Pour in the rice wine vinegar or lemon juice and add the lemon zest. The vinegar or lemon juice and the salt will create the contrast to prevent the sauce from tasting irritatingly sweet. The lemon zest will give the sauce a pleasant aroma.
Pour in a cup of water. Stir to dissolve the sugar and salt.
Set over medium heat, bring to the boil then lower the heat to medium-low and cook, uncovered, for 10 to 12 minutes.
The sweet chili sauce will appear watery after 10 to 12 minutes of cooking. DO NOT be tempted to cook it much longer. The sauce will turn syrupy as it cools. If you cook it until it is thick, by the time it cools, it will harden and no longer be pourable at all.
Cool the sweet chili sauce and enjoy.
If you’re wondering what the tiny black specks in the sauce is, that’s vanilla. You don’t have to add any. It’s just that we throw in vanilla beans into our jars of white sugar so all the white sugar in the house have those little black specks.
To store, pour the sauce into a jar (you can transfer it into a bottle but you will need to use a funnel). Cover and keep in the fridge.