How to cook an egg using the sun's energy?

The city is doing repair work in your neighborhood and they require the electricity to be shut off for a time. Your parents had planned to make egg salad sandwiches for lunch, but the eggs are not cooked, and without electricity, you can’t use the stove. Since it’s a sunny day, you decide to make a cooker that will use the Sun’s energy. How will you go about it? - Activity developed by Éclairs de sciences.