When I read your post, tacos instantly sprang to mind, so that must be the one thing for me. If I thought about it, I'd say steak, loaded baked potato and salad with ranch (think Lone Star, Outback, etc). But if you go with first instinct thought, it must be tacos.
For the one thing I'd starve before touching, not counting rhubarb because of allergies, it would be black pudding. I have tried it 11 times now, and still can't stand it. I was working on the thought that I hated broccoli with a passion as a kid, but tried it from time to time as I got older, and now it is one of my fave foods. It hasn't worked with black pudding, so I must just not like it.