For the pancake mix:
3½ cups (12¼ oz.) old-fashioned rolled oats
4 cups (1 lb.) white whole wheat flour
1 cup (4¼ oz.) unbleached all-purpose flour
3 tbsp. (1¼ oz.) sugar
3 tbsp. (1½ oz.) baking powder
1 tbsp. salt
1 tbsp. baking soda
¾ cup (5¼ oz.) vegetable or canola oil
To make the pancakes:
1 cup whole grain pancake mix (above)
¾ cup buttermilk (or ½ cup low-fat greek yogurt plus ¼ cup low-fat milk)
1 large egg, lightly beaten
1 tsp. vanilla extract
½ tsp. lemon zest
To make the pancake mix, add the oats to the bowl of a food processor and process until finely ground (but not a powder). Transfer the ground oats to the bowl of an electric mixer and add in the flours, sugar, baking powder, salt, and baking soda. Mix on low speed to combine. Drizzle the vegetable oil into the bowl slowly while the mixer is running and continue to mix until evenly combined and the mixture clumps slightly when squeezed together. (This can also be done in a regular mixing bowl by hand. Just be sure to mix the ingredients very thoroughly.)
Transfer the pancake mix to an airtight container. This can be stored up to 1 week at room temperature or indefinitely in the freezer.
To make the pancakes, mix together 1 cup of the pancake mix with the buttermilk, egg, vanilla and lemon zest. Whisk until the batter is mostly smooth. Let the batter stand at least 15-20 minutes before using, to allow the whole grains to soak up the liquid.
Heat a skillet or sauté pan over medium heat and grease lightly with butter. Ladle about 1/3 cup of batter onto the cooking surface for each pancake. Allow to cook until bubbles begin to form on the top surface. Use a large spatula to flip and cook the other side until light golden and cooked through. Repeat with the remaining batter and serve warm.