i think its a sensory issue, because for example i dont mind the taste of onion, but the second i feel it in my mouth i reflexively need to throw up. this goes for a LOT of food, and the food i can eat, needs to be prepared in a few specific ways. rare steak? throw up. well done? delicious. raw carrot? throw up. boiled carrot slices? tasty. and so on and so forth