Measure the flour into a glass or ceramic bowl and freeze for 15 minutes. Freeze the 3-tablespoon-size chunk of butter for 15 minutes. Put the 5 tablespoons of diced butter on a plate and refrigerate for 15 minutes. In a glass measuring cup, combine the yogurt and salt with 1 tablespoon of cold water and refrigerate for 15 minutes.
Using a pastry blender or two butter knives, cut the diced butter into the flour until the mixture resembles coarse meal. Using your hands, rub the mixture between your hands until all of the fat is evenly distributed and the mixture resembles fine oat flakes. Using a sharp knife or a cheese plane, very thinly slice the remaining 3 tablespoons of butter and freeze the slices for 5 minutes.
Add the butter slices to the bowl. Toss gently to separate the slices and cut once or twice to combine them with the flour; the slices should remain cold and intact. Drizzle the cold yogurt into the bowl, using a rubber spatula to stir and toss as you drizzle. Continue tossing the dough, scraping any off the spatula and the side of the bowl, until it is crumbly and evenly moistened. Press the dough into a 6-inch disk and wrap in plastic. Refrigerate the dough for at least 2 hours or overnight, or freeze for 1 month.