In a small sauce pan, mix together brown sugar and cornstarch. Set aside.
Zest and juice the lemon and the orange. Set aside zest of both. Measure out 1/3 cup of the orange juice and 2 1/2 tablespoons of the lemon juice (discard any extra or save for another use). Add juices to brown sugar mixture and cook over medium heat, stirring until slightly thickened and bubbly. Continue to stir for 1 minute then remove from heat. Transfer mixture to a small bowl; stir in vanilla and 1/2 teaspoon each of the orange and lemon zest. Chill for at least 1 hour.
Peel and section the two oranges. Place orange sections, pineapple, strawberries, kiwi, grapes and blueberries in a large bowl. Pour cooled sauce over fruit and gently toss to coat. Chill, covered for 2 to 3 hours before serving. Garnish with more zest if desired.