Most alcohol is vegan.
You can make a vegan chili with vegetable broth, black beans, pinto beans, vegan refried beans, onions, and peppers. We have it about once a month, and we are not vegan.
We also like to have a "salad bar" for meals at home about once a week. Not saying it's a great "special" meal for your son, but I thought I'd throw it out there. It's something that's easy to make vegan.