Place butter in a small bowl with the miso and lime juice. Smash with a fork to mix thoroughly. Taste and season with more miso if needed (but you probably won’t!).

Heat a frying pan or BBQ on a medium high heat. Rub fish with oil and sprinkle with a little salt, remembering the miso butter is pretty salty. Sear fish for 3-5 minutes on each side or until cooked to your liking.

Divide spinach / salad between two plates. Top with fish and smear the butter over your fish so that it melts to form an incredible sauce.