Preheat the oven to 180°C.
Place the nuts, flour and salt in the bowl of a food processor and process until the nuts are ground. Place the egg yolks and sugar in a bowl and beat for 3 minutes, or until the mixture is pale and creamy. Fold through the zest and coconut then the nut mixture. Place the egg whites in a clean, dry stainless steel bowl and whisk until stiff peaks form.
Using a large metal spoon, fold lightly through the nut batter.Spread the batter evenly into a 23cm greased or non-stick springform cake tin.
Bake for 40 minutes, or until the cake is lightly golden. Remove from the oven and leave to sit for 10 minutes in the tin. Turn the cake out onto a serving plate.
To make the lime icing, combine all the ingredients in a bowl and mix until smooth and glossy.
Spread the lime icing over the warm cake, allowing it to drizzle down the sides.
