Salt the fish and avocado, skewer the fish and avocado to create a wave pattern, brush with oil.
Charcoal/gas/electric grill: Grill the skewers all over for approx. 6 mins. over/on a medium heat.
Lemon balm oil
Puree all the ingredients or crush them using a mortar and pestle.
Drizzle the lemon balm oil over the plaice and avocado satay, serve the remainder of the oil alongside.