An ex-girlfriend in college showed me this trick. Take some Pillsbury Grands Buttermilk Biscuits, flatten them slightly, and use a cap off a sauce container (I used a cap 1" in diameter from a Johnny's French Dip container) to punch the hole. Heat about 1" deep of oil in a large skillet to medium high; I used canola but any flavorless oil works well, especially peanut. To make donut holes, combine two of the punches into one ball and fry them up as testers ... they should brown after 60 seconds or so on each side; I used two slotted wooden spoons to keep help them brown on all sides. Drop a few donuts at a time (three fit nicely in a 12" cast iron skillet) and fry until golden brown, then flip ... the donuts themselves take about 90 seconds per side. Remove and drain on paper towels and then you can toss them in powdered sugar, cinnamon sugar, etc.
I made a quick glaze with 1/2 cup powdered sugar, 1 tbsp salted butter, 1 tbsp unsweetened cocoa powder, 2 tsp peppermint extract, and 1 tbsp of 2% milk (plus a little more to thin it just slightly) over low heat in a nonstick saucepan to make a chocolate-mint glaze. Take the warm donuts and place face down in the chocolate mixture, let them sit for a few seconds, and rotate the donut (like you're unscrewing the lid on a pickle jar) to allow the glaze to coat evenly while releasing.
You can use other flavors than peppermint ... raspberry or rum extract go really well with the cocoa powder. I've even done banana extract with chocolate glaze and crushed peanuts (I called it the "A Hunk, a Hunk of Burning Love"). Also, Nutella by itself is KILLER as a donut icing.
If you're using recycled oil be sure it's been well filtered ... fishy donuts are no bueno. Let me know how you like them!