1.Preheat oven to 200°C/180°C fan-forced.
2.Pat fish dry, inside and out, with absorbent paper. Score fish four times both sides. Place lemon inside cavity.
3.Thinly slice fennel bulbs; reserve ¼ cup of the fronds.
4.Place fennel and red onion in large shallow baking dish; place fish on fennel mixture, drizzle with combined wine and oil. Roast, uncovered, about 30 minutes or until fish is cooked through.
5.Meanwhile, to make lemon dressing, combine ingredients in screw-top jar; shake well.
6.Combine mesclun, reserved fronds and green onion with dressing in large bowl.
7.Serve fish with fennel mixture and salad.
We used whole pink snapper in this recipe, but you can use any whole white fish.Note