[ridgeguy]

I'll speculate this is phase-controlled microwave cooking.

Microwave power transistors are now cheap at high power levels. If you have an array of such emitters, you can synthesize beams that can deposit energy in small, local volumes. This has been done in actively-scanned military radar for several decades. No moving parts, and beam steering in microseconds.

As a bonus, you could also run a pre-cooking process where you scan the food and map its microwave reflection/absorption properties. This would let you calculate the cooking algorithm based on the particular food item..