Saute onion in 2 T of the olive oil until soft. When soft add in the fresh herbs and saute until wilted.
Meanwhile Preheat oven to 190°C Rinse fish and pat dry. I then "butterflied" the fish the best I could to make it a bit flatter.
Season fish with salt and pep.
Lay the prosciutto slices vertically and slightly overlapping on a roasting tin, then put one of the monkfish fillets across, cut side up. Arrange the peppers and the herb mix on top of the fish. Then put the other fillet on top (cut side down), to make a parcel. Wrap the prosciutto around the fish, covering it completely.