Set each fish fillet (2) on a sheet of foil over 2 tbsp butter (4 tbsp). Top with a lemon slice (1), a drizzle of olive oil and a bunch of coriander (1).
Wrap tightly to steam in the juices. Cook on a hot frying pan or in a hot oven until cooked through, ~15 min.
Serve in the opened foil with vegetables alongside.