First mix the flour with dry yeast, salt, sugar and mashed potato powder. Then add enough water until the batter comes off the bowl. Then put the dough in the bowl (without a lid) in the refrigerator for 4 hours or overnight.
After the dough has risen, shape a loaf and prick several times with a fork. Then brush the bread with olive oil. Then sprinkle all over with hail salt. Bake for about 1 hour at approx. 180 ° C.