Bon Appetit Magazine had a great recipe for a lime angel food cake covered with crushed pistachios. It is very lengthy and detailed, so follow the link for the full recipe. I will simply outline the overall steps. Firstly, you have to use very fine ingredients. You want the cake to be as light as possible with a moist, soft texture. To that end, you combine four-times-sifted cake flour, superfine sugar and whipped egg whites with a little vanilla and lime zest. Be careful when mixing these ingredients. Their delicate nature means that things could easily go awry. Carefully fold the dry ingredients into the whipped egg whites so they don't lose their air or volume. Simultaneously, you have to make sure the dry ingredients are thoroughly mixed in. I undermixed at this stage, so my cake ended up with the occasional pocket that was less cakey and more sticky and chewy. It was not a terrible problem, but it definitely detracted a bit from the overall experience.
Next is the easy part - baking the cake. Then you allow it to cool completely. Be sure to a) use an angel food cake pan with a removable insert, and b) invert the pan after cooking. If the cake is not inverted, it will collapse because it does not have enough structure. Also take care if you put the cake atop a bottle to cool because it will be very top heavy.
You could probably stop here if you really wanted. The cake would be delicious by itself or with some fresh fruit or whipped cream. But to go the extra mile (since you've already worked so hard to sift, beat and otherwise coax your ingredients to form a beautiful cake), you make a lime simple syrup to act as the glue to hold the crushed pistachios all over the cakes surface. Lastly, you drizzle a lime glaze over it all.
It is definitely true that making an angel food cake from scratch is a bit of an ordeal compared to a white or chocolate cake. You have to spend more time and take more care to ensure that everything turns out just right. But in the end, you get to control what goes into the cake. You get to flavor the batter. Plus, you avoid all of the additives put into cake mixes. I think this cake turns out a lot lighter and airier in texture compared to the boxed mixes. It feels like you are eating a cloud. The lime flavors that permeate the cake as well as in the glaze add a fresh fruitiness. The pistachio flavor is more diffuse and the small nut bits add a little crunch to the outside. Overall, I'd say this cake was a heavenly success.