Heat a grill pan or barbecue to high, and brush the corn cobs with a little oil. Grill the corn on all sides until cooked through and slightly charred – about 12 minutes in total.
Run your knife down each cob to remove the kernels and place in a bowl, along with the capsicum, cucumber, spring onion, parsley and juice of 2 limes. Toss together and season with salt flakes to taste.
Slowly melt the butter in a heavy-based frying pan (cast iron is best for this). Brush each fish fillet with a little butter, then completely coat in the spice mixture.
Increase the heat until very hot, but not burning, and carefully place the fish fillets into the pan. Cook for about 1 – 2 minutes per side, depending on how thick the fish is, until the spice mix has gone very dark and crusty.
Remove from the pan.
Serve with corn salsa and lime wedges on the side.