In a medium bowl, combine coconut milk and lime zest and juice. Season each fillet with ½ teaspoon salt, then place them in coconut milk mixture and marinate for 20 minutes.
In a small bowl, gently toss diced onion and garlic powder with 1 teaspoon rapeseed oil and place in zone 2 drawer (with no crisper plate inserted).
Insert a crisper plate into zone 1. Remove cod from marinade and place on crisper plate. Select zone 1, select AIR FRY, set temperature to 190°C and set time to 20 minutes. Select zone 2, select ROAST, set temperature to 160°C and set time to 16 minutes. Select MATCH. Press the START/STOP button to begin cooking.
In a separate medium bowl, gently toss cauliflower rice, pepper, remaining salt and remaining rapeseed oil.
When zone 2 time reaches 10 minutes, remove drawer from unit and add cauliflower rice mixture to the onion and stir to combine. Reinsert drawer to continue cooking.
When cooking is complete, serve cauliflower rice in a bowl, gently placing cod fillets on top. Garnish with fresh coriander and chopped cashews, if desired.
