Thai sweet chile dipping sauce is made by simmering sugar, water, vinegar, garlic, and sliced Thai chiles until it turns glossy and lightly syrupy. It is a simple, sweet-hot sauce for fried food, grilled meat, fish, and shellfish.
Mix all ingredients together in a non-reactive bowl. Store in the refrigerator until needed.
NOTES
Simmer the sugar mixture first. Cook the water, vinegar, sugar, and salt until the sugar fully dissolves and the liquid has simmered for about 8 to 10 minutes.
Pulse the garlic and chiles small. Finely chopped pieces give the sauce a better texture than leaving them in big chunks.
Stop before it gets too thick. Cook it only until it just starts to look syrupy, because it thickens more as it cools.
Thin it if needed. If you reduce it too far, stir in a little water and check the seasoning again.
Use the chiles you have. Thai chiles are the standard here, but other hot red chiles work too. Just expect the heat level to change.
Store it in the fridge. It keeps for about 2 months once cooled and refrigerated.