Prepare couscous according to package directions.
Drain Greek salad mix, reserving 3 Tbsp. liquid. Combine Greek salad mix, reserved liquid, tuna, parsley, and lemon juice in a large bowl. Add couscous, and toss to coat. Serve with lemon wedges, if desired.
Note: We tested with Bumble Bee Premium Albacore Tuna in Water pouches and Gia Russa Greek Salad.