Whisk the flour, baking powder, and salt together in a large bowl.
In a separte bowl, whisk the milk, sour cream, and egg together, as well as the ground chipotle (if using). Whisk the wet ingredients into the dry ingredients, mixing just until you have a smooth, uniform batter. Fold in the corn and green onions.
Heat 1 tablespoon of oil in a heavy-bottom skillet or griddle over medium heat (assuming you will be frying these corn cakes in batches, I recommend adding approximately 1 tablespoon of oil to your pan before cooking each batch). Using 1/4-cup measure, portion out 3 or 4 corn cakes into the skillet. Fry corn cakes for approximately 3 minutes on the first side, until air holes appear across the top of each corn cake, and their shapes are set and matte colored. Flip and cook 3 to 4 more minutes, until corn cakes are cooked through. Serve immediately. Continue cooking batches of corn cakes until all the batter is used.
*I added ground chipotle because I love chipotle and corn together.