Preferred food for sinus problems?

There are saline nasal rinses that can be a big help to clear the sinuses. (Check your local pharmacy.) If the sinus issues are from allergies, Flonase is one prescription spray that can help prevent them from getting inflamed or congested.

What is the nature of the sinus problem?

leave off dairy.

Fresh onion. You don't even have to eat it, just cut it in half and leave it in a dish in the patient's room.