1) Preheat the oven to 425°F. Lightly grease a 9" cast iron skillet, or 8" round cake pan. The size of the pan matters here, so measure carefully. Too small, it'll overflow. Too large, it won't puff as high.
2) Melt the butter in the skillet, or melt the butter and pour it into the cake pan.
3) Whisk together the flour, salt, and sugar.
4) In a separate bowl, whisk together the milk, vanilla, and eggs.
5) Add the liquid ingredients to the dry ingredients, whisking until fairly smooth; a few small lumps are OK. Stir in the melted butter, and pour the batter into the pan.
6) Bake the pancake for 15 to 20 minutes, or until it's puffed and golden, with deeper brown patches.
5) Remove it from the oven, and sprinkle with the lemon juice, then the sugar.
6) Serve immediately, garnished with fresh berries.
7) Yield: 1 or 2 servings.