Last birthday, Scott was inspired to buy me a GoSun solar cooker. It is a vacuum insulated tube that is coated with copper inside. You load up your food into the 1m long metal tin, find a sunny spot on the deck, and away you go. I cooked a lemon cake in 40 minutes. We have also cooked rice and veggies very successfully, you can roast the veggies if you add olive oil, or steam in a little water.
We found the GoSun to be a real talking point on the town quay and a great icebreaker for meeting new people. The other day we came into Preveza town quay and a lovely German couple helped us with our lines. So to thank them, we cooked a cake and shared it with them over coffee.