Peel and cut your potatoes into small pieces and place in a pot. Add water to just cover the potatoes. Add a pinch of salt, and then bring the potatoes to the boil. Once boiling, lower the heat to medium and then simmer for approximately 10 minutes until the potatoes are fork tender.
Once your potatoes are tender drain. Add the potatoes back to the pot, along with the butter, and your buttermilk. Mash the potatoes until creamy and smooth. Then add salt and pepper to taste.
Last but not least add in your green onions and mix.
Serve this delicious champ with the traditional corned beef, or as a side dish to accompany any meat!