As much as I read, write and live gluten-free, some things still puzzle me. At the top of my list is vinegar.

When my son was diagnosed with celiac, the doctor warned us that vinegar could contain gluten. It seemed to be a taboo ingredient, and I was cautious of every product that contained it. Even a jar of pickles became, well, a pickle. Almost every product, especially condiments, contains "vinegar" among the ingredients, which had me asking myself a series of questions:

1. What is vinegar?

According to the Vinegar Institute: "Vinegar is made by two distinct biological processes, both the result of the action of harmless microorganisms (yeast and “Acetobacter”) that turn sugars (carbohydrates) into acetic acid. ... The first process is called alcoholic fermentation and occurs when yeasts change natural sugars to alcohol under controlled conditions. In the second process, a group of bacteria (called “Acetobacter”) converts the alcohol portion to acid. This is the acetic, or acid fermentation, that forms vinegar. Vinegar can be made from any fruit, or from any material containing sugar."

2. What can vinegar be made from?

Vinegar can be made from anything that can produce sugar. In the United States, it is most often derived from potatoes, corn and apples, but can also be made from malt or grapes. U.S. vinegar typically is not derived from wheat. The USDA lists what each kind of vinegar is derived from here. It looks like malt vinegar is the biggest no-no for those with celiac, not surprisingly. But I am also wary of rice vinegar, since it is not on the USDA list and may have "flavors" added to it.

3. What kind of vinegar is the "vinegar" on the label?

If the ingredient lists vinegar on the label, the USDA says it is apple cider vinegar, which is made from apples.

4. What is "distilled" vinegar?

Distillation is a separation process that consists of vigorous boiling. Some claim that even vinegar made from wheat is gluten-free if it's been distilled. White distilled vinegar has many uses, such as cleaning, killing weeds and disinfecting. White distilled vinegar is typically made from corn.

5. So, what can we eat?

After getting into the nitty-gritty of vinegar, I have come to the conclusion that most vinegars made in the United States are gluten-free. I know to avoid "flavored" vinegars and malt vinegar and that "vinegar" on the label is apple vinegar. I have bottles of apple cider, red wine and white distilled vinegar in my cupboard and stick to gluten-free brands I trust, such as Heinz and Kraft (they don't hide gluten in their products).

It still puzzles me whether "vinegar" can contain gluten, and I still have some questions, such as: Why is vinegar so taboo if most of it appears to be gluten-free? For now, I will stick to the brands I know are gluten-free.

Here is a yummy recipe that uses vinegar. I revamped it from a recipe I received via a Door-to-Door Organics email. I find it is crisp and delicious, and a good spring side dish.

Bok Choy Salad
3 stalks bok choy, stem and leaves, cut into bite-sized pieces
3 crisp apples, cut into bite-size pieces
1/4 cup walnuts, coarsely chopped
2 stalks celery, chopped
1 cup raisins

Dressing:
1/4 cup olive oil mayonnaise (Hellman's is gluten-free)
2 tablespoons sugar
3 tablespoons red wine vinegar (Heinz is gluten-free)
A splash of lemon juice
salt and pepper to taste

Chop veggies, walnuts and apples and place in large bowl. Whisk together dressing and toss with salad. It doesn't seem like a lot of dressing for the big bowl of veggies, but it will coat it all. Enjoy!

* Tip: In a large squirt bottle, pour 1/2 cup white distilled vinegar and 2 drops of your favorite dish soap and fill with water for a greener cleaning solution. Use on counter tops and cooking surfaces to disinfect and deodorize.