Microwave
The process of cooking foods through dielectric heating was in 1934 and the first commercial available microwave oven was the 'Radarange', which was offered for a whopping $5,000 in 1947 - equivalent to more than $50,000 in today's money. The Radarange was also less than practical for the home cook, weighing in at 340 kg, and standing at 1.8 metres tall.