I love mayonnaise and would have heaps of it with everything - if it wasn't so unhealthy! I have been experimenting with alternatives and have come across one that is not only nutritrious but tastes fab too - and seems to go with anything from fish to meat to veggies:
Greek yoghurt mixed with pomegranate seeds (bought ones obviously!) and lots of salt and pepper. Give it a try, it really seems to hit the spot!