Rinse any ice glaze from frozen Alaska Sole fillets under cold water; pat dry with paper towel.
Place fillets in a single layer on top of couscous. Brush each fillet with butter and top with lemon slices.
Cover pan and place in heated oven; roast 30 to 35 minutes for frozen fillets or 20 to 25 minutes for fresh/thawed fish. Cook just until fish is opaque throughout. Sprinkle with parsley before serving.
Cooks tip: Substitute Alaska Cod or Pollock fillets for Alaska Sole; adjust cook time for smaller fillets, if necessary.