The batter can also be prepared in a blender: Place the ingredients in the jar of a blender, then turn it on and off quickly. Scrape down flour from sides, and blend again until smooth.
To make the crepes: Place the flour in a bowl, and add the eggs, sugar, vanilla, and 1/2 cup of the milk. Whisk slowly until a smooth batter forms. Add remaining 1 cup milk, and whisk to combine. Cover, and refrigerate batter for 30 minutes or overnight. Just before using, whisk in melted butter.
Heat a 6-inch crepe pan, either well seasoned or with a nonstick surface, over medium heat. The pan is ready when a drop of water dances on the hot surface. Hold pan in one hand, tilting it slightly. Using a small ladle, pour about 2 tablespoons batter into pan where sides and bottom meet. Turn pan in a circular motion to spread batter evenly. The amount of batter used should just coat bottom of pan. Any excess should be poured back into bowl.
Cook the crepe until edges begin to brown, 2 to 3 minutes. Flip, and cook 10 to 15 seconds more. Slide onto a plate. The surface of the crepe should be medium brown in color. (If, after cooking 2 crepes, the color is too dark or too light, adjust heat accordingly. At the same point, if the crepes are too thick, thin batter with milk.) Repeat with remaining batter, stacking crepes on top of one another until all the batter is used. Allow crepes to cool.
To make lemon-zest strips: Using a channel knife and working from top to bottom, remove long strips from lemons. Try to keep the strips as intact as possible to yield about three strips (each 4 inches long) from each lemon. Bring a medium pot of water to a boil. Add lemon strips, and blanch for 30 seconds. Remove, and pat dry.
To make the purses: Place a crepe on a clean work surface. Fill with about 1 tablespoon creme patissiere. Gather edges of crepe up and around filling, creating a "beggar's purse." Tie purse closed with lemon-zest strip. Repeat with remaining crepes, creme patissiere, and lemon zest strips. If desired, reserve a few crepes to fill with berries when plating.
To serve, arrange purses on plates. Decorate plates with sauce au chocolate, raspberry coulis, or creme anglaise, if desired, and berries. An unfilled crepe, if using, can be folded and filled with diced berries.