In a medium saucepan, set over medium-low heat, heat sugar, stirring occasionally with a wooden spatula, for about 6 to 8 minutes, or until fully dissolved and caramel colored. Quickly pour onto bottom of individual ramekins, swirling around the bottom to coat each one.
Preheat oven to 350°F. In the jar of a blender, or in a mixing bowl stirring energetically with a whisk, combine evaporated milk, sweetened condensed milk, eggs, orange juice, orange zest and vanilla. Pour into prepared ramekins and place them in a large baking dish or roasting pan; fill the roasting pan with hot water to about 1-inch depth. Cover the roasting pan lightly with aluminum foil.
Bake for 50 minutes. Remove from the oven, remove the aluminum foil, and let cool. Remove each ramekin from the water bath, I use a pair of tongs to do so. Let the flans cool completely before covering with plastic wrap and placing in the refrigerator. Refrigerate at least 2 hours before serving.
When ready to eat, run a small knife around the edge of each flan. Invert dessert plate over ramekin, flip over and shake slightly to release. Leave the ramekin on top of the flan for a minute or so, so all of the caramel sauce can run over the flan. You may garnish with orange sections.