Please note that for certain ingredients, I list measurements in two ways: first, by volume (cups, tablespoons); second, be weight. If you have a kitchen scale, you should weigh the flour; otherwise, measure the flour in a cup measure designed for dry ingredients.

Steps

1. Cut the butter into ½-inch cubes, spread out on a plate, and freeze for about 15 minutes.
2. Mixer method: Combine the flour and the butter in a stand mixer fitted with the paddle attachment. Mix on low speed until the butter cubes are smashed up a bit and the chunks are about half their original size; don’t worry if the chunks aren’t uniform. Stir together the water, lemon juice, and salt until the salt is dissolved; then, with the mixer running, slowly pour it into the flour and butter and mix just until the dough barely holds together; it will look quite shaggy. Don’t add all the liquid until you’re sure you need it. The dough may seem a little dry at first, but it will come together as you start rolling.
3. Hand method: Toss the flour and butter in a wide bowl and cut the butter into smaller pieces with a bench knife, pastry scraper, or table knife. Pinch and press the mixture with your fingers to encourage the butter to form flattened pieces. Stir together the water, lemon juice, and salt until the salt is dissolved, then gradually add the liquid as you toss the flour mixture with a fork to evenly distribute the liquid. Your goal is a shaggy dough that just holds together.
4. Dump the dough onto a floured counter and pat it into a rough rectangle about 5 by 8 inches. Roll into a 5-by-15 inch rectangle, lifting the dough after every few rolls to be sure it’s not sticking to the counter and dusting the counter with more flour if it is sticking.
5. With a soft pastry brush, brush off any excess flour from the surface, then fold the bottom third of the dough up and the top third down, like you’re folding a letter. Make sure all the corners are square and all the edges of the dough line up neatly so the three layers are in perfect alignment. Turn the dough 90 degrees to the right, so that the open edge is on your left. This rolling, folding, and turning is called a “single turn.”
6. Repeat the rolling and folding for three more single turns, each time neatening up the edges of the dough with your palms to keep them straight and snugging up the corners so they’re square, as well as brushing off excess flour before you fold. Dust the block of pastry with more flour, wrap it in plastic, and chill for at least 30 minutes.
7. Repeat for two final single turns, then chill at least another 30 minutes before rolling and baking.