To make dough: In a medium bowl, sift together flour, baking powder and salt. Cut in shortening with a pastry blender or two knives, until mixture resembles coarse crumbs. Stir in milk, a little at a time, and mix well. Knead briefly. Set aside.
For filling: In a medium bowl, stir together cherries, sugar, cinnamon and lemon zest until well mixed.
On a floured surface, roll the dough into a rectangle 1/4 inch thick. Brush with melted butter. Spread the cherry filling evenly over the surface of the dough, leaving 1/2 inch around the edges. Roll up the dough, starting at a short end, and pinch together all the edges so that the juice will not escape. Wrap roll in a kitchen towel or cheesecloth and tie loosely.
Place in a steamer or colander over boiling water, cover and steam for 90 minutes, until dough is firm. Remove cloth, slice and serve.