Masa biscuits

3 3/4   c            Unbleached A-P flour
   1 1/2   c            Masa harina de maiz
   2       tb           Plus 1 ts baking powder
   1       t            Salt
   4       oz           Unsalted butter, well-chill
                        -cut into small pieces
     1/2   c            Solid vegetable shortening,
                        -well-chilled, cut into
                        -small pieces
   2       c            Cultured buttermilk,chilled

  Position racks in the upper and middle thirds of the
  oven and preheat the oven to 450F.
  
  In a large bowl, stir together 3 1/2 cups of the
  flour, the masa, baking powder, and salt.  With a
  pastry cutter, blend in the butter and shortening
  until the mixture resembles a coarse and slightly
  lumpy meal. Stir in the buttermilk until a soft,
  crumbly dough is formed.  Sprinkle the work surface
  with half of the remaining flour.  Turn the dough out,
  gather it into a ball, and briefly knead it, just
  until it holds together. Flatten the dough, sprinkle
  it with the rest of the flour, and roll it out about
  1-inch thick.  With a round 3-inch cutter, form the
  biscuits, transferrring them to 2 ungreased baking
  sheets and spacing them about 2 inches apart. Gather
  the scraps into a ball, roll it out to 1-inch thick,
  and cut out the remaining biscuits.
  
  Set the baking sheets on the racks and bake about 15
  minutes, exchanging the position of the sheets on the
  racks from top to bottom and from front to back at the
  halfway point, or until the biscuits are golden and
  crisp. Serve hot or warm.
  
  Note: masa is NOT the same thing as cornmeal.  Stores
  catering to Hispanic population will have masa.  Since
  masa contains no gluten, these biscuits are especially
  tender.