Preheat oven to 425 degrees F (220 degrees C). Line a baking sheet with parchment paper.
Whisk flour, sugar, baking powder, salt, and baking soda together in a bowl. Cut in butter with a knife until mixture resembles coarse crumbs.
Place the bowl in the freezer for 5 minutes.
Stir in Greek yogurt until dough is combined. Add 1/4 cup seltzer; mix until dough is smooth. Add more seltzer if dough appears dry.
Place dough on a floured piece of parchment paper and pat into a flat rectangle. Fold the rectangle in thirds. Rotate dough 90 degrees, gather any crumbs, and flatten into a rectangle again. Repeat folding, turning, and flattening twice more.
Flatten dough to 1/2-inch thickness. Cut into twelve 2 1/2-inch rounds. Transfer rounds to a baking sheet.
Bake in the preheated oven until golden brown, 10 to 15 minutes.
If using unsalted butter, add 1 teaspoon salt.
If not baking all biscuits, place on parchment paper in a resealable plastic bag and freeze for up to a week. When ready to eat, bake as you would fresh biscuits.
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