A Medium onion
A dash or two of vinegar (cider or balsamic)
A blob of mustard
A jar of mayonnaise
A kg of waxy potatoes (Nicola variety are best)
Finely chop the onion and soften in a pan with oil or margarine, until soft. Don’t let them brown. Add a little water then stir in the Mayonnaise (start with a couple of tablespoons – you can always add more). Add a dash or two of vinegar and a blob of mustard, salt & pepper.
Halve or quarter the boiled potatoes (leaving the potatoes on for added texture and taste) and mix into the onion & mayo mixture. If the sauce is too thick, just add a little more water or vinegar to adjust.
For extra creaminess use some a couple of tablespoons of Sojasun (crème fraiche) or yoghurt.
Traditionally served with Weiner sausages and pickled gherkins.