Combine the sugar and water in a medium saucepan. Cook over medium heat until the sugar is completely dissolved. Bring the liquid to a boil without stirring until the syrup begins to change color.
When the syrup begins to turn light amber, turn off the heat and add the room-temperature orange juice and orange zest. Stir and incorporate the juice carefully. The syrup may initially clump a bit but will smooth out in a few minutes.
Let the syrup cool.
Place the fruit in a glass bowl. Add the syrup and toss.
Portion the fruit into 6 bowls and top with a dollop of the yogurt and serve.