Wash and peel one large red onion. Slice off the root edges, and cut them into two halves. Then, slice each half into ¼-inch thick slices. Use your fingers or a fork to separate the slices into thin rings.
Preheat the oven to 400°F. While the oven is heating, spread the onion slices / rings evenly, neatly spaced out in an oven-proof baking dish or a cast iron skillet. Toss the slices with avocado oil, and toss to coat. Then, add a teaspoon of salt, and ½ teaspoon each of black pepper and garlic powder and use your hands or a fork to toss them and spread them out evenly.
Roast the onions for about 10 minutes. Then, stir once and then continue roasting for another 10 or so minutes, until the onions are tender and caramelized, and starting to get crispy on the sides! Serve as a side or snack!
You can also use a mild yellow onion in this recipe but I prefer using a red onion since it turns out sweeter when caramelized!
I prefer using avocado oil since it has a high smoke point and can withstand 400F oven temperatures without smoking. Olive oil works fine in the recipe if you reduce the temperature of the oven to 375F and roast for 25 to 30 minutes instead!
You can use a glass or ceramic baking dish or a cast iron skillet. I find that using a cast iron skillet creates crispier edges, but make sure to use an enameled one or ensure that the bottom is coated in a thin layer of oil to prevent any sticking!