In a small sauce pan bring the water to the boil and add salt.
Add the garlic cloves to the boiling water for 30 seconds. Then scoop the garlic out of the water with a slotted spoon and place in a small sterile jar.
Add the mustard seeds, sugar, and chili flakes to the garlic and pour over the vinegar.
Fasten the lid. Make sure the jar is at room temperature, then place the jar in the refrigerator.
For best flavor, allow the chili pickled garlic to set for 24 to 72 hours before opening the jar.
Notes
Keep in the refrigerator sealed for up to a month. Once opened use within 2 weeks.