We have the most common of the two types… that is “just” a convection oven w/fan. Coil in the ceiling, fans circulate the heat. Essentially a badass toaster oven… that IS absolutely brilliant for everything you’d cook in a toaster oven or a regular oven. ESPECIALLY chicken, as you can make wings that don’t need to be steamed first, to fry in their own fat and crispy up… but it is sooooo NOT good for anything you would actually deep fry.
The fan means it also works as a food dehydrator, although my attempts at jerky have so far failed it’s great with fruit/veg. It has a rotisserie option but the rotisserie basket would fit one Cornish Game Hen. Nothing bigger. So it doesn’t ever get used. Similarly the rotisserie prongs are too fiddly, needing perfectly balanced food, for me to bother with.
As a toaster oven on steroids? It’s badass.
As a dehydrator it has potential.
As a “fryer” or rotisserie? Pfft. Nope!
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The kind of air fryer that you ADD oil to a little 1/3 cup thing, and it sprays a fine mist over your food as you cook it? And circulates the oil/steam to keep reinjecting it? DOES work really well on fried foods, as long as the batter is dry or frozen. Wet batters still won’t work.