Vegetable oil(I used coconut oil and really liked the taste and results)
Heat oven to 300º to keep pancakes warm. Whisk first 6 dry ingredients together in a bowl. Make a well in center, pour the buttermilk into the well and then crack the two eggs into the buttermilk. Pour the melted butter into mixture. Start in the center and whisk toward the outside of the bowl until all is incorporated. Do not overmix, lumps are totally expected and just fine. Coat blueberries in 1 teaspoon of flour and add to cornmeal batter.
Heat a large skillet, griddle or cast iron pan on low heat for about 5 minutes. Turn heat up to medium and add 1 tablespoon oil. Ladle ⅓ cup batter into skillet, and repeat, being careful not to crowd pancakes. (I could fit 3 on my griddle.)
Carefully flip pancakes when full of bubbles and bottoms are nicely browned, about 3 to 4 minutes. Cook another 2 to 3 minutes on other side until lightly browned. Remove pancakes to wire rack inside a baking sheet and keep in oven until all pancakes are done and ready to serve. Add more oil as necessary.
Dust with powdered sugar if you like, and serve with butter and pure maple syrup. Enjoy.