For pastry, stir oats, flour and salt, then cut in lard until mixture resembles coarse crumbs. Blend in water and form into ball of dough with fingertips.
Let stand 5 minutes, then roll to fit an 8 or 9" pie plate. It is a bit tender to lift, so pass a spatula under as you fold it in two. If it breaks, simply join it together.
To fill, stir apples, brown sugar, and cinnamon. Pack into pie shell.
To top, mix oats, flour, brown sugar and cinnamon. Cut in margarine until mixture is crumb-like, then cover apples.
Bake for 35 minutes at 375 degrees F, or until golden brown on top.