In a large bowl mix together the flour, baking powder, baking soda, orange peel, and salt. Cut in butter with a pastry blender or two knives until the mixture resembles coarse crumbs.

Toss the raisins in the sugar and then add to the other dry ingredients, mixing well. In a small bowl mix the egg yolk and buttermilk together. Pour over the flour mixture and stir just enough to blend evenly.

Turn the dough onto a lightly floured kitchen counter and knead gently for about 10 minutes. Pat the dough into a 1-inch thick round onto an ungreased 10-by-15 inch baking sheet. With a sharp knife, cut the round into 12 wedges. Bake in a preheated 375-degree oven for 25 to 35 minutes.