Trim the spring onions, removing roots & green leaves, leaving about 8 cm of white part.
Preheat oven to 180C (350F).
Pat fish dry with paper towel. Lay 2 strips pancetta side by side & place salmon on pancetta. Fold one end of the strips of pancetta over the fish, then roll the fish over to complete the portion. The pancetta folds should be on the underside of the fish.
Heat half the olive oil over a medium heat in large frying pan. Place the fish, service side down, in the pan, pressing to ensure complete contact with the pan. Cook for 4 minutes, before turning carefully and cooking for another 2 minutes.
Remove the fish from the pan, place on an oven tray and put into the oven for 4-5 minutes.
Fry the spring onions in the remaining oil until golden, add beans and saute for 1-2 minutes. Season with salt and pepper.
Divide the beans and place onto 4 plates, top with the salmon and drizzle with the saba.