Wash, then cube potatoes on a chopping board. Wash and cube bell pepper, celery into small slices, sweet pickle into small triangles, set aside.
Boil a litre of salted water and add in the potatoes, cooking for 5-8 minutes, or until a fork easily pokes through. Drain in a colander and transfer to a large, clean salad bowl, leave to cool for 5-10 minutes.
Add in the remaining veggies followed by pickle water, mustard and mayo, then sprinkle in the seasonings.
With a spoon or salad tongs, combine the potatoes with the rest of the ingredients and seasonings, until well coated.
Leave to set for 5 minutes and serve while warm, alternatively you can cover and transfer to the fridge and chill for an hour or two beforehand – Depending on your preference!