Preheat oven to 350oF (180 oC). In a small heavy saucepan, combine half the sugar and the water. Cook over medium heat, stirring constantly, until sugar is dissolved. (Do not let mixture boil while stirring.) Increase heat to medium high and boil, without stirring, until mixture caramelizes and is golden in colour, 6 to 8 minutes. Pour immediately into an 8 inch (20 cm) rounded baking dish, tilting pan to cover bottom. In a bowl, whisk eggs with remaining sugar until blended. Stir in hot milk, orange rind and vanilla. Avoid overmixing. Pour into pan over caramel mixture. Place in a pan of boiling water and bake until mixture is set, 40 to 45 minutes. Remove from hot water. Cool on a rack. Cover with foil or plastic wrap and refrigerate overnight. To remove from mold, run spatula carefully around custard. Invert a rimmed serving plate over custard and turn over. Serve in wedges.