Hi Ged
Thanks for your message and sorry to hear about your allergic reaction.
You can, of course, sue a restaurant if they're responsible for triggering your allergic reaction. In your case, it looks as if you made the request and the restaurant accepted it. You, therefore, trust them to relay that information to the kitchen and to take greater care when preparing your meal. If this didn't happen, the restaurant could be seen to be in breach of their duty of care.
If you'd like help making a claim, please get in touch with our expert team by either using the live chat, bottom right, or by calling us on 0800 073 8804.
You can also click here.
I hope that helps!
Edward