Boil 8 medium/large potatoes with skins on until they are tender, not mashed potato soft but soft enough to cut through, approximately 45 minutes.
While your potatoes are cooking, cook up this tangy and delicious sauce, but take care you don’t cook on too high a heat or you will cook the eggs wrong.
In a medium saucepan melt butter until just starting to brown. (My own addition since it always ends up browned for me.)
In a bowl stir sugar, cornstarch, ground mustard.
Add white vinegar, eggs and water. Mix well so the sugar partially dissolves.
Add liquid to butter and constantly stir over medium heat until thickened.
Pop in the refrigerator and cool.
Mix vegetables and potatoes together.
Pull cooled sauce from refrigerator and add mayonnaise.
Whisk well until no lumps.
Pour over potato and vegetables and mix well.
Refrigerate overnight or 8 hours so the flavors mix well.