Sushi, that's what a solar cooker is.

"...if anyone has any experience with cooking using a fresnel lens."

The main problem with a fresnel lens seems to be that sunlight is directed from above, not the best way to cook.

But I wonder if you could make a solar cooker out of bricks (okay, it's not very portable) with a linear fresnel lens angled to focus on the edge of a black cast-iron "cooking plate", with a metal container sitting on that?

You could call it 'ray-gun cooking'! ;-)