Asthma symptoms aggravated after eating raw onions. Cooked onions ok. Vinegar and sauerkraut can cause symptoms. Any other foods to avoid? Allergy?

Not necessarily. It sounds like these acidic and irritating foods may be just irritating your airways. This doesn't necessarily mean that you're allergic to them, although you should probably still avoid them or pre-treat with your asthma inhaler prior to indulging. See an allergist to be properly tested to ensure this isn't an allergy that is emerging and proceed as they suggest.
Leeks and garlic. Be careful with any thing in the onion family. Shallots besides above. The foods you are eating with vinegar may be spiced with onion/garlic powder. Remove all of these from your diet for a week and observe level of asthma control. Remember sauces (ketchup, mustard) if accidental exposures trigger asthma symptoms continue to avoid it. Then try back a small amount and watch for 24 hours.
Depends.... What foods to avoid depends on what foods you are allergic to. You can sometimes have a clue as to what you are allergic to via allergy testing. Unfortunately, sometimes you will have a reaction to a food as your first indication of an allergy. Keep track of which foods cause a reaction and avoid those. See your doctor since you may need an epi-pen depending on what sxs you have as a reaction.