1.Whisk dry ingredients: In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt until very well combined, about 30 seconds.
2.Combine wet ingredients: In a large measuring cup, beat together buttermilk, lemon juice, eggs, and melted and cooled butter.
3.Mix wet ingredients into dry: Make a well in dry ingredients; stir in wet mixture until lumpy and just combined. Let rest 10 minutes.
4.Preheat oven, heat skillet: Preheat oven to 200°F and place a rimmed baking sheet fitted with a wire rack inside. Heat a large nonstick or cast-iron skillet over medium; add oil, then wipe with a paper towel, leaving behind a thin film.
5.Cook pancakes in batches: Working in batches, add heaping quarter-cups of batter to skillet, spreading lightly with the bottom of the cup. Cook until bubbles form on surface, edges have set, and undersides are golden-brown, 2 to 3 minutes.
6.Flip and finish cooking; keep warm while cooking more pancakes: Flip and cook 2 minutes more. Transfer finished pancakes to oven to keep warm. Serve a tall stack with softened butter and maple syrup.