Prepare caramel: In a small heavy saucepan, dissolve 1/2-cup sugar in 2 tablespoons water. Cook over medium-high heat until sugar melts and turns medium brown. Don't stir, just shake pan around. Immediately pour caramel into a 5-cup ring mold. With oven mitts on both hands, rotate mold gently, swirling caramel to cover bottom and some of the sides, keep moving mold around until caramel is almost set.
Preheat oven to 350 degrees F.
Combine milk, vanilla bean and lemon peel in a saucepan and cook over low heat for 10 minutes. Cover and set aside for 15 minutes.
In a blender or food processor, beat egg yolks, eggs and remaining 3/4-cup sugar until light and foamy. Discard vanilla bean and lemon peel. Pour hot milk into egg mixture in a slow steady stream, beating constantly. Stir in brandy or orange liqueur. Immediately pour mixture into mold and place it inside a larger pan filled with boiling water halfway up the mold.
Bake in preheated oven for 50 minutes or until a cake tester comes out clean. Let flan cool at room temperature and chill.
To assemble the dish, un-mold flan onto a dessert platter with a rim. Spoon caramel left in mold on top of flan. Serve at room temperature or chilled.