Halve the potatoes with skin.
Heat sufficient water in a deep non-stick pan, add halved potatoes, sea salt and 2 tbsps vinegar. Cover and boil till the potatoes are soft. Drain and set aside.
Roughly chop spring onions and greens separately.
Heat butter in another non-stick pan. Add spring onion bulbs and boiled potatoes and mix well.
Add sea salt, salt and crushed peppercorns, mix, cover and cook on high heat till potatoes are light brown.
Add spring onion greens and 2 tsps vinegar, mix well and cook for 2 minutes.
Add 1 tsp vinegar, mix well and cook for 1 minute.
Transfer into a serving bowl and serve hot.