With a pastry cutter, cut in shortening and pesto until mixture resembles coarse crumbs.
Make a well in the center; add water all at once. Stir in just until dough clings together. Turn out onto a lightly floured surface.
Knead gently for 10 to 12 strokes. Roll or pat to 1/2-inch thickness.
Cut with a 2 1/2-inch biscuit cutter, dipping cutter into flour between cuts.
Place biscuits on an ungreased baking sheet. Bake in a 450ºF oven for 8 to 10 minutes or until golden.
Makes 10 to 12 biscuits.