How to Solar Caramelize Perfect Rooftop Peaches and Plums

Summer is nearly over, but the time is still ripe for peaches, plum and nectarines. My favorite way to take advantage of the end of stone fruit season and the last rays of summer sunshine is with the perfect lazy person’s culinary method: solar cooking. A few hours in a solar oven can transform even mealy or bruised fruit into pure caramelized goodness.

It’s easy to adapt any basic fruit caramelization recipe, like this one for caramelized plums, for a solar cooker. The method is very simple, and I like to improvise. Most recently, I sliced two nectarines and a large plum into thin wedges and mixed them with a dash of lemon, approximately two teaspoons of butter, and a tablespoon of brown sugar. Then came the fun part — cooking with Mr. Sun.

For successful solar cooking, you need four things: direct sunlight, a reflector, a dark pot or pan with a lid and a glass or plastic covering. As an apartment-dwelling urbanite, I don’t have a yard or balcony on which to catch direct rays, so I make do by crawling through my second-floor kitchen window to set up my solar oven on the roof of the adjoining one-story building.

For my reflector, I use an oven called a CooKit. Originally designed for use in refugee camps where sun is plentiful and fuel is scarce, the CooKit is a fold-up piece of reflective cardboard that optimizes the angles of reflection to concentrate sunlight in a small cooking area. You can buy one from Solar Cookers International, which uses the profits to support its water pasteurization programs in East Africa, or you can DIY with cardboard, aluminum foil, and a downloadable pattern.

The CooKit can reach up to 250 degrees Fahrenheit, which isn’t nearly as toasty as a conventional oven, but is plenty warm to cook anything from stone fruit to biscuits to chicken curry given enough hours of direct sunlight. More advanced solar oven models can achieve much higher temperatures, and there’s even a type of parabolic reflector that gets hot enough to cremate a body. As I didn’t have anything to cremate, my intrepid little CooKit was perfect for the task at hand. I took it out onto the roof, unfolded it, and angled it towards the sun.

In order to absorb the heat reflected by the walls of the oven, I cooked my nectarines and plum in a thin, black baking pan. I enclosed the pan in a turkey sized oven bag and closed it tightly with a clothespin. The humble oven bag is actually crucial; it traps the heat and helps the food achieve and maintain the highest temperature possible.

With my fruits and solar cooker in place, I just…left it all alone. As my stone fruits slowly caramelized, I finished washing the dishes, went for a run, took a shower, and watched several episodes of The Great British Baking Show. Two hours in, I rotated the CooKit slightly, but other than that, the cooking process required nothing of me. In total, I cooked the fruit for about four hours, until it was very soft and fragrant. It’s almost impossible to burn or overcook anything in a solar cooker like mine. The temperature simply isn’t high enough.

A long afternoon in the sun can bring out the best in stone fruits. Cooked slowly in their own juices (with the help of a little butter and sugar), the plum and nectarines achieved a rich, robust flavor without becoming too sweet or syrupy. With a light, melt-in-your mouth texture, they went down easy. Too easy, perhaps. As you might imagine, my caramelized stone fruits didn’t last long. I served them hot from the rooftop with vanilla ice cream. All in all, an eco-friendly and highly delicious way to celebrate summer’s last gasp.

Molly Jean Bennett is a writer and multimedia producer based in New York City. Her essays, poems, and strongly worded letters have appeared in McSweeney’s Internet Tendency, Atlas Obscura, VICE, and elsewhere. Her chapbook Paper Apartment is forthcoming from Essay Press. Follow her on Twitter via @MollyJeanBee.