Combine the base ingredients. In a small saucepan, mix water, sugar, rice vinegar, and chili flakes. Heat over medium until sugar dissolves.
Add garlic. Stir in minced garlic and cook for 30–60 seconds until fragrant. Don’t burn it; burnt garlic is sad garlic.
Optional thickening. If you like a thicker sauce, dissolve cornstarch in a teaspoon of water and stir into the pan. Simmer for 1–2 minutes until glossy.
Add ketchup (optional). Stir in for extra color and subtle sweetness.
Season and taste. Add salt, then taste. Adjust sugar or chili if needed. Balance is everything.
Cool and serve. Let the sauce cool slightly. Serve warm or at room temp as a dip, drizzle, or glaze.
