Hidden gluten 2.
Conventional Asian soy sauce is made with (gluten-containing) wheat as well as gluten-free soy. Gluten-free soy sauces are available.
Any product with “malt” on its label or as an ingredient is suspect of containing gluten. This includes malt vinegars.
Distilled vinegars are gluten-free, all other vinegars suspect. Note that condiments like mustard and ketchup usually contain vinegar. Read the label.
Dried mustard powder, curry powder, and many pre-ground spices like white pepper often have wheat flour added to prevent caking.
Instant coffee can have added wheat to bulk up the package.
Even ground meats are sometimes bulked up with gluten products.