Solution for uneven heating on an electric coil stovetop

I wok on an electric stove and have found there's a few tips to really help - its not perfect, but it helps:

• Preheat, preheat, preheat. Before you start any of your prep, put your wok on the stove and crank the heat. Let it heat up before you do anything at all to it.

• Make sure everything is at least at room temperature. We often use frozen stir fry veggies, but we thaw them out first and they're at least at room temp before they go in. The same goes for meat. For sauces, we'll often microwave it so that its a bit warm before it even goes in. If you have a screaming hot wok, and you add cold food - then for a long time it will only steam the food.

• Do it in batches. Don't crowd your wok until everything is already hot. If you're doing meat and veggies - do the meat first, take it off, let the pan reheat, and then do some of the veggies. Work in batches so that the pan temperature doesn't drop and give it time to reheat between batches. Assemble it all at the end.

The burners on essentially all electric stoves are binary in that they are either fully on, or fully off. It would be more expensive and less energy efficient to use electronics that continuously vary the current flow through an electric element, and this would make no significant difference in temperature behavior at the cooking surface. Instead, electric stoves use a bimetallic switch which is a relatively simple way to have an on-off pattern with variable on/off times. To create constant heat, all electric stoves use materials that are bad conductors of heat between the electric element and the cookware surface to buffer the huge temperature swings at the element and produce very steady heat at the cooking surface.

The difference you are seeing between electric coil heating elements and glass-ceramic cooktops is that in the electric coils there is an inner heating element, then a thick ceramic layer, followed by an outer layer of metal. The element itself is heated in a binary manner, but all you can observe is the heat after the buffering of the ceramic layer has made up for the large fluctuations at the element (i.e. the outer metal glowing fairly constantly once it's heated). In a glass-ceramic cooktop, since the buffer layer (the glass-ceramic surface) is translucent, you are seeing the actual element glow (often this is an infrared lamp instead of a resistive wire) so you are viewing the non-buffered heating pattern. If you had a clear coil, you'd see the same heating on/off patterns in a coil stove as you do in glass-ceramic.

Consequently, if you measure the surface temperature of a glass ceramic cooktop, you should see a fairly constant temperature.