Place the rolled oats, flour, sugar, baking soda, and
salt into a large bowl.  With two knives, cut the 
butter into the dry ingredients -- or mix until 
crumbly with your hands. You can also do this by
processing in a food processor for 10 to 20 seconds.
When the mixture resembles coarse meal, add the 
cold water, a little at a time, blending well after each addition.  The dough should be stiff. 

Cover a pastry board or cloth with additional rolled 
oats.  Turn the dough out and roll about 1/8-1/4" thick. Cut into 3" circles or squares.  Arrange them on baking sheets. 

Bake until slightly browned in an oven preheated to 
375*, about 10-15 minutes.    Watch carefully, as they
burn easily.  Slide the cakes from the baking sheets 
and cool on wire racks.

Makes about 18 cakes.

Note:  This recipe can be made vegan by using
soy margarine instead of butter.