OK, this recipe uses caustic soda. So live dangerously! This is from Michael Ruhlman, a fine food writer, the picture above by his wife Donna. I used regular caustic soda, not even food grade, and it worked fine. If you are afraid to use cs, try a 1:10 solution of sodium bicarbonate, but they won't have the classic pretzel aroma and taste. You can get food-grade sodium hydroxide or cs from a chemist shop. The other interesting part is the 5:3 stanfard bread dough. With this you can make bread, pizza, focaccia (add some olive oil), and so on.
500g of GP flour
300 cc of water
This will give you a basic 5:3 bread dough
3 grams dry yeast, or slightly more if you need a quick rise.
12 grams kosher salt
4 teaspoons of food grade caustic soda dissolved in 750 ml of water
Vegetable oil or spray
Very coarse sea salt (or kosher salt) as needed
Non-reactive bakeware - glass, ceramic or silicone.
Mix the flour, water, yeast and salt until you have a smooth elastic dough. Cover it and let it rise to about double it's volume, 2 to 4 hours depending on how much yeast you've used. Beat it down manfully to release the gas and redistribute the yeast. Divide the dough into roughly 90-gram portions.
Preheat your oven to 210 degrees C.
Roll each portion into a cylinder about 15 long. Cover them with a towel while you prepare the caustic soda and ready some non-reactive baking sheets - don't use metal sheets, caustic soda can do funny things to it. Heat the cs solution in a pan that will allow you to dip your pretzels and retrieve them with a wide, slotted spatula. Coat the baking surfaces with vegetable oil.
After the dough pieces have rested for 10 minutes, roll them out into 30 cm long cylinders. To make the pretzel shape, lift either end, make one complete twist, then fold them over into the traditional pretzel shape. See the picture above. Bear in mind they will double in size.
When the lye solution is hot, just below a simmer, dip each pretzel in the cs solution for 10 to 15 seconds, then remove to your baking pan. Repeat with the others, sprinkle them with salt and bake for 12 to 15 minutes.