Heat the oven to 400°.
Cut 6 pieces of parchment paper large enough to hold the fish fillets and to be folded securely to keep moisture in.
In a bowl, mix the onions, fresh herbs and spices (except for the bay leaves).
Melt the butter and brush the inside of each piece of parchment paper before adding the fish.
Distribute the onion, herb and spice mixture between the fish packages and place the tomatoes, peppers, bay leaves and lemon slices on top of the fillets.
Mix the lemon juice, olive oil and wine or liqueur and pour over the fillets, distributing evenly between the packages.
Season lightly with salt and pepper.
Close the packages by first bringing together the edges along the long side of the fillet and folding over each other to create a tight seal.
Follow by folding in the loose edges downward 2 to 3 times so that the seal faces down.
Moisten the tops of the packages with a little water to seal better.
Place the packages on an ovenproof dish or tray and bake for about 20 to 25 minutes.
Place the individual packages on plates, open slightly to allow the steam to escape and serve immediately.