Why do you need to mix the lye with boiling water? I have checked other recipes and they don't mention this, so I'm just wondering what the reason...

I'm not sure why the recipe instructs to dissolve the lye in boiling water first. When mixed with water, it's an exothermic reaction, ie. the solution gets hot. This is the reason you mix lye into water and not other way round (water into lye). I guess it speeds up the dissolution of the lye but I think that mixing with room temperature water and cooling it down in an ice bath, would be just as effective. Even with that small amount of lye, I'm not feeling very confident with mixing lye with boiling water. That reaction gets quite hot even with cool water water.

Last year, I took a pretzel & bagel workshop that had us producing almost 5 dozen bagels and pretzels per person. We were even instructed on using lye vs baking soda. Surprisingly, I preferred the pretzels made with the baking soda solution. I've always been a big fan of the lye-dipped pretzels so when I actually tasted the baking soda, it was a revelation. Now, I don't have to deal with lye which is expensive to ship (I swear the shipment cost alone was twice as much as the food grade lye that I ordered). My favorite pretzel was the one stuffed with ham and grated gruyere.

Perfect - thank you for the detailed answer! I will definitely try it and have already ordered the lye on Amazon. :)

Traditional pretzels are dipped in a lye bath so they will achieve the crust and color associated with pretzels. As it comes as a powdery crystal, if you dumped it into a large pot of water as is, it would react quite violently and you'd likely get burned badly. It is best mixed slowly into cold water first, to dissolve, and then added to the hotter water. This creates an very diluted alkali solution. The alkali changes the exterior of the dough. The bath also helps the dough achieve the typical pretzel chew. You can also somewhat achieve this effect by using baking soda in the bath water, although it won't be exactly the same because the pH you get with baking soda is lower than what you will get with the lye. But if you skip the step entirely, your pretzels will never get the same deep brown golden color, or the chew you are looking for. Your pretzels will turn out pale. The only reason I can think of for putting formed pretzels in a refrigerator would be to lengthen the rising time, because longer rising times help improve flavor. It may also be an effort to increase the amount of time the risen pretzels can stand being in the hot bath, making it a bit easier on a baker who wants to do larger batches. I don't think it is a strictly necessary step. I've made traditional pretzels loads of times and never put the formed pretzels in the frig. If you do opt to use the lye, it is VERY important that you use a food grade lye, and dilute it as directed. The diluted lye on the pretzels is safe to eat because it is highly diluted and starts out very pure and clean. The lye sold for cleaning and clearing pipes is NOT safe for food use. If you can't find food grade lye, then use baking soda instead. 2/3 cup of baking soda per 10 cups of water makes an acceptable bath if you wish to avoid lye, or can't source it. It's not quite the same as lye, but still quite acceptable.