There are plenty of cool solar ovens on the market these days. Most of them only work during the day. The GoSun Sport-E works all day and night. It can cook your food in under 20 minutes. This 7lb oven has a stay-cool vacuum cooking tube. It folds up for portability.
The GoSun Sport-E Cooker reaches temperatures up to 350F. It can cook enough food for two people. When the weather is not cooperating, you can simply plug in this cooker to a 12V DC power source. This project is currently getting funding on Kickstarter.