1. Whisk together 1/4 cup olive oil and next 5 ingredients; set aside.
2. Stuff the cavity of the fish with lemon slices and fennel fronds. Secure with wooden picks.
3. Place fish in large shallow pan; pour marinade over fish, turning to coat. Let stand 15 minutes.
4. Dust fish evenly on both sides with flour. Grill fish on oiled grates over high heat (450°-500°), turning halfway through cooking time, approximately 10 minutes per inch of thickness or until the flesh separates easily from the bones but is still moist. Serve with lemon wedges and olive oil.