In a large frying pan, combine the 1 cup water, orange juice, lemon juice and ginger.
Bring to a boil, then reduce the heat to a simmer.
Add the fish and simmer for 5 minutes, or until the fish flakes easily with a fork.
Use a slotted spoon or spatula to remove the fish to a serving plate.
In a cup, dissolve the cornstarch in the 2 tablespoons water.
Add to the liquid in the pan.
Bring to a boil and stir until slightly thickened.
Serve over the fish.