If you mix pancake batter too energetically or for too long, you overdevelop the gluten in the flour and your pancakes will be tougher than necessary. Excess blending can also cause the premature formation, and escape, of the carbon dioxide that you need for leavening the pancakes.
A much better strategy is to stop mixing the ingredients just before all the tiny lumps of flour dissolve and then let the process automatically complete itself as the batter sits undisturbed in your refrigerator. The cold refrigerator temperature not only retards bacterial attack and growth but impedes gluten development and hinders the yeast or baking powder activity.
A smooth batter produces more than just desirable texture. It also helps to brown your morning masterpieces more evenly because a greater area of the bottom surface will rest flat on the hot griddle.
** Asian Recipes