In a large bowl, combine the flour, sugar, baking soda and salt. Cut in shortening until mixture resembles fine crumbs. Stir in milk and lemon juice just until moistened. Turn onto a lightly floured surface; knead 8-10 times. , Roll out to 1/2-in. thickness; cut with a floured 2-1/2-in. biscuit cutter. Place 2 in. apart on ungreased baking sheets. Bake at 450° until golden brown, 8-10 minutes., Meanwhile, in a small bowl, combine lemon butter ingredients until blended. Serve with warm biscuits.