Scrub the potatoes and throw the potatoes into a pan with salty, boiling water; boil for 10-12 minutes until tender; drain and set aside while you make the dressing
Put the sugar and vinegar in a bowl and stir until the sugar has dissolved; add some black pepper, mix in the mustard, then beat in the olive oil; stir in the parsley and set aside; chop the spring onions and celery
Halve or quarter the warm potatoes and throw into the dressing; fold them in gently with the spring onions and celery and seeds if using; serve no more than 20 minutes later
4 servings