Cool idea!
I use to have a solar oven that was an insulated box - black inside with a little rack in the middle to set your food on. It had large fan shaped reflectors on it that caught all the sun's rays and reflected it into the black box part. There was a plexiglass window in the front of the box.
Point it at the sun and it works like a charm easily getting the oven over 300 degrees.
Great for hot summer days when you don't want to heat up you house.