Peel, wash and slice the potatoes thinly. Boil 2 cups water with half teaspoon salt. Turn off the heat, add potatoes and cover. Keep this for 3 minutes, then drain and put on a clean kitchen towel.
Dissolve the sugar in warm water. Add yeast. Cover this for 15 minutes till it turns frothy.
Mix in the flours. Add half the quantity of chopped mint. Add water and knead for 5 to 7 minutes to get a soft and supple dough. Oil one big size bowl and transfer the dough into it. Cover and let it rise for 1 hour to 1 and ½ hours or till doubled.
Preheat oven to 190 degrees Celsius. Grease one baking tray.
Punch down the dough gently and turn it out into the prepared tray. Stretch the dough to a rectangle big enough to fit into the baking tray. Brush dough with 2 to 2 ½ tablespoons of olive oil. Sprinkle remaining mint leaves.
Allow dough to rest for 10 minutes. Arrange potato slices on the dough, pressing them down gently. Brush the potato slices with remaining olive oil. Sprinkle remaining mint leaves. Sprinkle salt over the dough evenly.
Cover and let the dough rise for 20 to 30 minutes. Bake it for 20 to 30 minutes or until it turns golden from top.
Cool in the rack. Slice. Serve warm or cold.