Preheat the oven to 350°F. Lightly grease (or line with parchment) two baking sheets., Beat together the shortening, sugars, egg, vanilla, and peanut butter until smooth., Add the flour, baking soda, and salt to the peanut-butter mixture, beating gently until everything is well combined. It may take awhile for this rather dry dough to come together; and when it does, it'll be quite stiff. Only if necessary, drizzle in enough water to make the dough cohesive., Drop the cookie dough by tablespoonfuls onto the prepared baking sheets (a tablespoon cookie scoop works well here), leaving 2" between them., Use a fork to flatten each cookie to about 1/2" thick, making a cross-hatch design., Bake the cookies for 12 to 16 minutes, until they're barely beginning to brown around the edges; the tops won't have browned. Remove them from the oven, and cool on a rack.