First pulse the flour and salt - and yes please weigh the flour! Then add the butter all at once. Pulse around 10 times, remove the lid, and check the size of the butter pieces by dipping a fork into the flour. they should be around size of a pea. Whisk together the sour cream and apple cider vinegar, and add all at once. Pulse a few times, and check the dough before adding the ice water. Pinch some of the flour mixture between your fingers. If it's ready, it should form a piece of dough without falling apart. If it crumbles start adding a little water, 1 tablespoon at a time. Go here
for a step-by step, including rolling the dough out, with pictures.