I will definitely do some testing by cutting up more raw veggies (only testing one per day, so I can make sure to test them in isolation), but I want to wait until my lips have healed a bit. If I tested now on my scrufty-looking lips (they are still scrufty and peeling from the stir-fry night sudden explosion), it would be hard to tell if there was any new reaction on top of the old reaction.
I do think it's probably the garlic.
I cook with onion at least twice a week, and I've cooked with onion several times in the last couple weeks while my lips were doing great, and it didn't seem to bother them.
If it's the garlic, I wonder if it makes a difference as to whether it's cooked or raw. I hope that I can eat cooked garlic at least, or otherwise that is going to be hard to avoid.