Lime & chilli butter
Using the whisk on a hand mixer, beat the butter for approx. 2 mins. until light and creamy.
Stir in the lime zest, lime juice, chilli and salt. Place the butter on a piece of clingfilm, sprinkle with the amaranth, shape into a roll, refrigerate for approx. 30 mins.
Rinse the fish (inside and out) in cold water, pat dry, brush with oil.
Charcoal/gas/electric grill: Cover and grill the fish over/on a medium heat (approx. 200 °C for approx. 8 mins. on each side (see note).
To serve, fillet the fish, season, serve with the lime & chilli butter.