Whisk together dry ingredients in a large bowl. Whisk together yolks and milk in a small bowl, then whisk into dry ingredients. Beat egg whites in another large bowl with an electric mixer until they hold soft peaks, then fold into flour mixture. Add 3 tablespoons butter and fold until batter is smooth. Lightly brush a 10- to 12-inch nonstick skillet with some of remaining butter, then heat over moderate heat until hot but not smoking. Working in batches of 4, spoon about 1 1/2 tablespoons batter per pancake into skillet and cook until surface of pancakes bubbles, 1 to 2 minutes, then flip and cook 1 minute more. Transfer to a plate and keep warm, covered. Brush skillet with butter between batches. Stir together all topping ingredients except salmon until combined, then dollop on pancakes and top with salmon. *Available at natural foods stores.