The recipe calls for:
fat-free greek yogurt
-- Clean the potato and poke a few holes in it. Cover with a paper towel and microwave for 3 minutes, more if it's a bigger potato.
-- Spread some olive oil on the potato and wrap in foil. If you want more of a grill taste skip the foil.
-- Grill the potato away from the fire while cooking everything else on the grill.
-- Slice it open, spray a little butter and a dabble of greek yogurt.
Greek yogurt is the perfect substitute for sour cream. It's way more healthy, has zero fat and is a great source of protein. I really don't taste much of a difference surprisingly. I bet you could even fool the kids or your husband by just telling them it's sour cream.