Dry fish with paper towels. Salt and season fillets. Add butter and oil to skillet over medium heat. Peel thick strips of lemon zest into the oil and let fry for 3 minutes. Remove zest and turn heat to medium-high. Add fish to pan and fry till golden brown, flip and fry for two more minutes.

Salt and season fish filets and put them aside. Spread out heavy-duty aluminum foil and sprinkle onions, then fish, then squeeze lemon onto fish and place lemon chunks on top. Fold up aluminum foil into a pouch and place over fire. Cook until fish is cooked. A good test is to gently poke a thick part of the fillet with a fork. If the meat pulls apart with a gentle pressure, it’s done.