Divide pastry into 24 balls. Place each ball in an ungreased 1 3/4-inch muffin tin; press into tins to form shells. Set aside.
tins to form shells. Set aside. Cream butter; gradually add sugar, beating well. Add egg, vanilla, and salt; beat well. Stir in pecans. Spoon 1 1/2 teaspoons filling into each tart shell. Bake at 350° for 25 minutes. Cool completely in pans.