1. In a food processor or blender, pulse macadamia nuts and salt until finely ground. Pour nut mixture onto a plate, and coat fish fillets on both sides.
2. Heat butter in a large oven safe skillet over medium heat. Fry fillets on both sides until nuts are golden brown. Be careful not to burn as the fats in this dish only tolerate medium temperatures. Place in preheated oven for 5 minutes.
3. Place ½ cup mixed greens on a plate. Top with fish and garnish with avocado slices.