Peel and cut the potatoes in chunks. Boil them or, much much better, steam them - adding a sprig of rosemary to the water.

Cut the pancetta into thin strips and place it in a pan over medium/low heat. Brown it until crunchy.

When potatoes are tender, mash them. Add the kefir, olive oil, and salt to taste (not too salty, because pancetta is coming) and mix well. 

Finally, add the pancetta flakes, amalgamate and serve hot.