Start your solar-cooking adventures with this easy, delicious, and safe recipe. Rabbit-Nest Sun Carrots have a bold, bright flavor that will please adults and adventurous kids. It’s safe because the sun’s heat is captured by dark chard leaves instead of messy and possibly toxic paint on the outside of the jar. If the sky is cloudy or you’d rather not cook with the sun, see the microwaving and stove-top tips below.
Finding safe, dark cookware
Many instructions for solar cooking insist on dark cookware or jars painted black. Paint can be toxic, fragile, and a mess. When I started experimenting with solar cookers, I asked my local hardware store for non-toxic, high-temperature paint. Once home, I was shocked to read in the fine print that the paint might interfere with an embryo’s development or cause other health problems.
I returned that paint and sought the help of my art-store guru. She recommended RAS acrylic color, which is rated ACMI non-toxic. But a quick google revealed this warning about ACMI non-toxic certification:
Do not eat, drink or smoke while using art and craft materials. Wash up after use – Clean yourself and your supplies. Never use products for skin painting or food preparation unless indicated that the product is meant to be used in this way.
Reading that and thinking about how the paint would get on my hands and in my lungs when I took the hot jar out of the roasting bag made me pause before painting.
Thinking inside the jar
Fortunately, my Taster is also a mechanical engineer. He said painting the jar black can help the jar get a little hotter in the sun, but not much. The hot jar passes heat on to the food, at least as much of it as can make it through the glass.
Then my Taster asked the magic question:
Why not use the sun to heat the food directly instead of heating the jar?
He explained that when you let the short waves of visible sunlight go through the glass to heat up the food, the hot food will radiate longer infra-red waves. The infra-red waves can’t go through the glass, so they bounce around inside the container and keep the food hot.
I launched a series of tests with dark food inside a clear jar. The rabbit nest — dark green chard leaves lining a jar top to bottom — works like a charm. You could use kale, collards or other greens too. Another test showed that putting a clear jar in a dark stocking actually lowered the temperature compared to the same food in a clear jar.
I hope you’ll try this fun technique as an experiment or as a way to serve hot food when the power is out. See my review of solar cookers if you don’t already have one on hand.