Fold the packet closed sealing it so the steam doesn't escape.
Repeat for the other 2 fillets making 2 packets total.
Grill over a medium flame for about 10 minutes. Remove from heat and let it sit for 5.
Open the foil and viola! The fish is cooked and the couscous underneath soaked up the lemon juice and steam. Some of the couscous also toasted on the edges making a fun texture and nutty flavor.
I served with some frozen Brussels sprouts I cooked on the grill.