Lemon Provencal Baked Snapper

Ingredients:

• 1/2 small thinly sliced fennel bulb, divided
• 1/2 small thinly sliced red onion, divided
• 4 (6-ounce) red snapper or tuna fillets
• 8 slices fresh lemon
• 1/2 cup olive-caper simmer sauce
• 8 fresh tarragon or thyme sprigs
• 2 cups cooked couscous

Source