In a bowl, sift together the flour and salt. Add in the water and 4 tablespoons of the butter. Use your fingers to gently work the dough into a ball. Wrap the ball in plastic wrap and stick in the refrigerator for 30 minutes.
Lay down a 12″ piece of parchment paper. Place the remaining 16 tablespoons of butter on top of the parchment paper and cover with a second piece of parchment. Use a rolling pin to shape the butter into a 5″ x 8″ rectangle-ish. Place in the refrigerator for 30 minutes to chill slightly.
Now, remove the ball of dough from the refrigerator. Cut a large ‘X’ in the top of the ball and pull each corner out, like you’re opening a gift box! This will help to begin the rectangle shape were aiming for. Lightly flour your work surface and begin to gently roll the dough out into a 10″ square-ish, rectangle shape.
Place the flattened butter in the center of the dough and fold in the corners. Roll out gently to combine the butter and the dough into a rectangle. Turn the dough so that a short side of the rectangle is facing you – fold the dough into thirds, like an envelope. Gently roll this into a rectangle. Cover with plastic wrap and refrigerate for 30 minutes.
Remove the dough from the refrigerator, fold it into thirds again, and gently roll into a 8″ x 12″ rectangle. Cover with plastic wrap and refrigerate for 30 minutes.
Repeat the folding/rolling/chilling routine 5 more times. You know what we’re doing here? We’re building layers of flaky dough. Each time we fold and roll, we’re creating a new layer of buttery awesomeness.
The dough can be held in the refrigerator for 3 days or in the freezer for up to 1 month! Bake according to your recipe that is calling for the puff pastry.