1Preheat oven to moderate, 180 C. Line an oven trat with baking paper.
2Place nuts, oil, garlic and zest in a small food processor. Pulse until mixture resembles coarse breadcrumbs. Season to taste.
3Place potato and celeriac in a saucepan of cold water. Bring to boil, remove from heat. Cover with a tight lid, set aside 10 mins. Drain well, cool. Peel potato.
4Meanwhile, place fish on tray. Divide nut mixture among fish and press down firmly. Bake 8-10 mins until fish flakes easily when tested with a fork in the thickest part. Grate potato and celeriac into a bowl and season to taste. Mix well.
5In a large frying pan, heat butter on high. Place 1/3 cup measures of mixture into pan, flattening with a spatula. Cook 2-3 mins until golden. Turn and cook 1-2 mins. Drain on paper towel. Repeat with remaining mixture.
6In a small saucepan, bring cream to boil on high. Stir in lemon juice and tarragon. Simmer 2-3 mins until slightly thickened. Serve fish with rosti, asparagus and sauce.
TIP: Use any greens of choice. You can also replace macadamias with almonds or hazelnuts.
Photo Credit: James Moffatt/Bauer