Lots of ginger, onions, and garlic.
Raw garlic is supposed to be better (but not as easy to eat imo). I love raw garlic in home made guacamole and hummus.
You could try making congee, I've never made it, but it is supposed to be very good for the immune system.
Not a food, but we have been enjoying a tonic of ginger tea, local honey, lemon juice, and water. My kids and I love it, and it's great for the immune system.
I hope you feel better and...