Here is a cruller donut recipe of mini crullers. You use a large star piping tip and a piping bag to form the crullers.
Have ready a cooking sheet lined with donut sized pieces of greased parchment paper.
Combine sugar, salt, butter, and boiling water in a saucepan.
Mix and bring to a rapid boil.
Add flour all at once and mix and cook until thickened, stirring constantly.
Remove from heat. Add eggs one at a time, beating thoroughly after each addition.
Add vanilla extract.
Put the mixture into a pastry tube fitted with a large flower piping tip. Force mixture through pastry tube onto greased paper, forming circles. Be sure to close the circles. Don't make them too large, these are meant to be mini sized crullers.
Heat the oil to 375 degrees F on frying thermometer. You will only cook 2 to 3 crullers at a time so the pot only needs to be large enough to fit that amount at a time.
If you put too many, you may have trouble keeping them from burning.
Carefully turn a paper with a piped cruller donut upside down so crullers will slide into the hot oil. Be very careful it does not splash up as it will burn you.
Cook until brown on one side then flip over and cook until golden brown on the second side.
Remove with tongs onto a plate lined with paper towels.
Drizzle on icing while still a little warm.
These crullers are the best when they are warm.
Stir half the milk, vanilla and confectioners' sugar together. If it needs to be more runny add the milk a little bit at a time.
Drizzle onto the donuts.