1. Heat oven to 150C fan-forced (170C conventional). Separate the egg yolks and whites. Sift the flour, baking powder and salt into a large bowl, and stir in 200g of the sugar, zest and coconut. In another bowl, combine the yolks, oil, coconut cream, rosewater and vanilla and set aside.

2. In a large bowl, beat the egg whites with an electric mixer until foamy. Add the cream of tartar and beat until soft peaks form (1-2 minutes). Gradually add the remaining 100g of caster sugar a tablespoon at a time, beating until firm and glossy (2-3 minutes).

3. Beat the egg yolk mixture (you can use the same beaters) until combined. Make a well in the centre of the flour mixture, pour in the egg yolk mixture, and bring together with a whisk, beating until smooth.

4. Fold in one-third of the egg whites to lighten, then gently fold in another third, then the final third. Pour the batter into an ungreased chiffon cake tin and bake for 55-60 minutes or until the top springs back to the touch and an inserted skewer comes out clean.

5. Remove the tin from the oven and turn upside down so each of the tin's three "legs" rests on a can (see tips). Leave to cool completely, then run a sharp knife around the edges of the tin, invert, and lift away from the base. Run the knife between cake and base and remove the base. Place the cake flat-side up on a wire rack.

6. To make the glaze, stir lime juice and rosewater into the icing sugar. Whisk in the sour cream a spoonful at a time, until oozy rather than runny. Spoon over the cake, allowing it to dribble down the sides. Scatter with shredded coconut and leave for 1 hour to set.

Tips

Cut the cake with a serrated knife; a regular blade will push the cake down.

You need to have the right cake tin – a 25cm chiffon cake tin (also known as an angel food tin) with a central funnel and removable base, available from specialist cookware shops such as Cake Bake Decorate, Sugar Time and Williams Sonoma.

You have to turn the baked cake upside down to cool as soon as you take it from the oven (so scary). Before baking, set up a bench area with three same-height cans so you can rest the tin's three little metal legs (or the rim of the tin) on them.

Turning the cake upside down to cool enables the egg proteins to stretch, resulting in an exceptionally light, tender crumb. Do not grease the tin or the cake will sink – or worse, fall straight out of the inverted tin.

Chiffon cake lasts for days in or out of the fridge! Can also freeze without harm.