Scrubbing And Leave Whole. Pierce Each Potato With A Fork To Allow Steam To Escape. Place A 1/4 Cup Water In A Microwavable Dish And Add Potatoes. Cover And Cook For 10 To 12 Minutes, On High. Stir After 5 Minutes. Let Stand For 10 Minutes To Cool. Cut Thin Slice From Each Potato. Scoop Out About 1 Tablespoon Potato From Each Potato. Mash Scooped Out Potato With Fork; Stir In Yogurt And Pepper. Fill Each Potato Shell With Mixture. Arrange On A Microwavable Plate And Cook For 2 To 3 Minutes. Sprinkle With Walnuts Or Ham.