1 yellow onion, thinly sliced
1 white onion, thinly sliced
2 tablespoons soy sauce or ketchup
3 cloves garlic, crushed
3 tablespoons cornstarch
1 tablespoon vegetable oil
1 1/2 tablespoons Worcestershire sauce
1 teaspoon white sugar
1 teaspoon salt
Place yellow onion and white onion slices in the smaller of two steamer spoons or bowls. Cover and steam for 1 minute.
In a small bowl, mix soy sauce, garlic, cornstarch, oil, Worcestershire sauce, sugar, salt and soy sauce mixture until well blended.
Remove onion and pepper slices from steamer, and pour mixture over sliced slices of leek.
Grill over medium heat for 5 minutes on each side or until fish flakes easily with a fork.
Cover and refrigerate for 15 minutes.