1. Drain the whitebait well.
2. Whisk the egg and mayonnaise until smooth.
3. Add the celery salt, flour and spring onion, lastly whitebait and fold gently together.
4. Heat a medium frying pan and add a little of the butter and oil. Add tablespoons of mixture to the pan, leaving room to expand. Cook the fritters for 2-3 minutes each side until puffed and golden.
5. Combine mayonnaise, lime juice and zest, capers and chopped coriander, mix well and season with cracked pepper.