Pre. Clip a candy thermometer onto a 2-quart saucepan so that its sensor hits the bottom of the inside wall of the pan. Fill the saucepan halfway with canola oil. Heat over medium heat on the stovetop until the candy thermometer reads 350℉. Reduce the heat to medium-low. While the oil is heating, set a wire rack over a sheet pan near the stove.
Make the cinnamon sugar. Next to the wire rack, place a large mixing bowl. Fill the mixing bowl with the sugar and cinnamon and mix together.
Fry. Gently scoop 1 cup of Duros into the hot oil. They will sink to the bottom of the saucepan and remain unchanged for a few seconds. Then, they will suddenly puff up and float to the top of the oil. Once all of the Duros reach the top of the oil (this will happen fast), count to 20, flipping them occasionally, before scooping them out with a spider skimmer and spreading them over the wire rack.
Coat in cinnamon sugar. Give the oil a few seconds to drain from the fried Duros. Once cool enough to handle, transfer the fried twists to the bowl with cinnamon sugar and toss to coat. Transfer to a large serving bowl.
Make the remaining cinnamon twists. Repeat steps 3 and 4 twice, frying 1 cup of Duros at a time.
Notes
Duros can be found at Mexican markets or sometimes in the Hispanic section of the local grocery store and come in different shapes too like the spiral duros.