Choose scallions with small white parts for the best texture.
If you cannot find garlic vinegar, make your own by boiling 2 cups white vinegar, pouring it into a sterilized glass jar, adding 4 bruised unblemished garlic cloves, sealing, and storing in a cool dark place for 3-6 weeks. Strain before use.
The scallions will have a unique "squeaky" texture when eaten, which is normal and part of the fun.