In a large bowl, mix flour, sugar, baking soda, and salt. Add the buttermilk, egg yolks, lemon juice, and lemon peel. Mix until evenly moistened. Gently stir in ricotta cheese. In a bowl, with a mixer on high speed, beat the egg whites until soft peaks form. With a flexible spatula, gently fold the whites into the batter just until they are incorporated. Next, add the blueberries. Gently stir in to combine. Place a large, nonstick frying pan over medium heat; when hot, coat lightly with oil and adjust heat to maintain temperature. Drop batter onto the pan and cook until pancakes are browned on the bottom and edges begin to look dry, about 2 minutes. Flip pancakes with a wide spatula and brown other sides, 1 1/2 to 2 minutes longer. Coat pan with more oil as necessary to cook remaining pancakes. Serve with caramel-butter syrup (http://ihearteating.com/2012/01/28/caramel-butter-syrup/), maple syrup, or blueberry compote (recipe below).