These are a softer, puffy texture (firmer on the outside) but will still work well for a sandwich that isn't too heavy or "soupy" (i.e. sliced deli meats are perfect, but a thick hamburger would probably be too heavy).
CLOUD BREAD
3 large eggs
1/4 tsp. cream of tartar
1/4 tsp. Kosher salt
1/3 cup plain Greek yogurt
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Pre-heat oven to 300° F. Line a large baking sheet with parchment paper.
Separate egg yolks from egg whites, letting the whites go into your electric mixer bowl and put the yolks into another medium bowl (and set aside). Add cream of tartar to egg whites. Beat on high until stiff peaks form, about 2-3 minutes.
Add the salt and yogurt to the bowl with the egg yolks. Whisk well until they’re well blended. Now, gently fold 1/3 of the beaten egg whites into egg yolk mixture (I use a rubber scraper). Fold in the remaining egg white mixture until just incorporated, being careful not to overmix.
Divide batter into 4 mounds on your baking sheet. Gently spread each one out with the back of a spoon, until you have a thick circle about 5-6” in diameter. (Note: You could make smaller 3” wide circles using about 1/4 cup batter for each one, if you’d rather have 6-8 smaller pieces of Cloud Bread).
Bake for 20-25 minutes, or until golden brown and exterior is crispy to the touch. Immediately loosen cloud breads with a spatula; allow to cool on the baking sheet for 3 minutes, then transfer to a wire rack to cool completely. (Don't leave them on the parchment paper-lined baking sheets longer, or they could stick to it. And, they need the air circulation to let the bottoms cool so they don't get soggy.)
Serve immediately, or store in an airtight container. Makes 4 big slices