For browned corn, in a 12-inch nonstick skillet, heat 1 Tbsp. oil over medium heat. Add the corn kernels in an even layer; sprinkle generously with salt. Cook, without stirring, for 3 to 4 minutes until the kernels sizzle. Shake the pan and continue cooking about 16 minutes total, until kernels are browned. Set aside 2 Tbsp. of the browned corn to top cooked griddle cakes.
Meanwhile, in a medium bowl whisk together flour, cornmeal, 1/4 tsp salt, and the baking powder. Whisk in milk, egg, and the 1 Tbsp. vegetable oil, mixing just until batter is smooth. Stir in chopped onion and the browned corn.
Wipe out skillet with a lightly oiled paper towel. Heat over medium heat. For each batch of cakes, drop batter by 1 or 2 Tbsp. measure. Cook about 1 minute, until browned on one side and batter appears set. Turn and cook about 1 minute (or less.) Cover and set aside griddle cakes to keep warm while cooking remaining batches.
Top griddle cakes with sour cream, if desired, chopped tomato, reserved browned corn kernels, sliced green onion, and the ricotta salata or feta cheese. Makes 6 side-dish servings.