In a medium bowl combine pastry flour, cornmeal, rolled oats, brown sugar, baking powder, and salt. Make a well in the center of the flour mixture; set aside.
In a small bowl whisk together egg, milk, and oil. Add the egg mixture all at once to the flour mixture. Stir just until moistened (batter should be lumpy).
Lightly coat an unheated griddle or large skillet with cooking spray. Heat griddle over medium heat. For each pancake, pour a scant 1/4 cup of the batter onto the hot griddle; spread to a 3- to 3-1/2-inch circle. Cook over medium heat for 2 to 4 minutes or until pancakes are golden brown, turning to second sides when pancakes have bubbly surfaces and slightly dry edges.
Meanwhile, for sauce, in a blender or food processor combine 2 cups of the strawberries, the rhubarb, granulated sugar, and vanilla. Cover and blend or process until smooth. Transfer to a small saucepan; heat until warm. Quarter the remaining 1 cup strawberries. Serve pancakes with sauce and quartered strawberries.