01 -
Combine sugar, vinegar, juice, and salt in a wide, heavy-duty pot. Slowly bring everything to a simmer over medium heat.
02 -
Add minced garlic, chili flakes, and ketchup. Allow the mixture to bubble for about 5 minutes, keeping the heat at medium.
03 -
Turn the heat to low. Gradually stir in the cornstarch mixture, making sure it blends smoothly without clumps.
04 -
Keep stirring it gently over low heat until it thickens to your liking. It will firm up even more as it cools, so don't overcook it.
05 -
Allow the sauce to completely cool. Pour it into a cleaned, sterilized bottle and store it in the fridge.