In a medium bowl, stir together the flour and salt. Cut the butter and/or shortening into pieces and add to the flour (I like to slice it in with a paring knife, or if it's firm enough, you could grate it on the coarse side of a box grater) and use a fork, pastry blender or your fingers to blend the mixture until you have a rubbly texture, with some fat blended in and some in pieces about the size of a blueberry.
Drizzle the water overtop and gently stir from the outside, sort of gathering the mixture together until it forms a dough. Handling it minimally (don't knead it) gather the dough into a disc, wrap it in plastic or cover with a tea towel and let rest for at least 20 minutes, or chill for longer. (If it's very warm or your pastry is soft, stick it in the fridge, otherwise it's OK to rest on the countertop.) Your pastry can be prepared up to this point and frozen for up to 4 months; let it thaw on the countertop when you need it.
Makes enough for a single crust pie or galette or about a dozen tarts.