For the custard: Using a vegetable peeler, cut colored part of oranges in wide strips. Combine milk, half-and-half and sugar in medium saucepan. Cut vanilla bean in half and scrape seeds into milk; add bean. Simmer, stirring until sugar dissolves. Add orange peel, remove from heat and let stand for 30 minutes.
Strain mixture into medium bowl and cool to lukewarm. Whisk eggs and yolks in large bowl. Gradually whisk milk mixture into eggs. Chill until cold.
For the caramel: Mix the sugar, water and lemon juice in heavy saucepan. Stir over medium-low heat until sugar dissolves. Bring to a boil without stirring until syrup turns deep amber, occasionally swirling pan and brushing down sides with a wet pastry brush, 6 to 10 minutes. Add 3 tablespoons water (mix will bubble). Stir over low heat until hard bits dissolve.
Pour immediately into a 6-cup souffle dish. Swirl to coat bottom and 1/2 up the sides. Preheat oven to 350F.
Whisk custard; pour into caremel-coated dish. Place in large baking pan, filled with enough hot water to come halfway up sides of the dish. Cover pan completely with foil, sealing at edges. Bake until center 3 inches of custard moves only slightly when shaken, about 1 hour. Remove from water and chill.
Cut pith off oranges and release segments. Run a thin knife around sides of custard and turn onto a platter with a lip. Garnish with orange slices and candied orange peel if desired.
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