After much nagging from my family, and quite a few lacklustre or outright failed attempts, I might finally have cracked the way to make proper pretzels as we know them from our old life (and holidays) in Bavaria.

I ended up roughly following this recipe (in German), but there were a few snags I had to work out to make it really work.

A tricky one is to do with the fact that the recipe asks for two tablespoons of Natron – which is actual pure caustic soda. This gets dissolved in boiling water and the pretzels are cooked for 20-30 seconds before being baked – this gives them the brown crust and the typical taste. The German name Laugenbrezel literally translates to lye pretzel – so that alkaline bath is pretty important.

Pure caustic soda is surprisingly hard to find in the UK. Sure, you can get drain cleaner, which is caustic soda, but it might have impurities you woulnd’t want to find on your food. Caustic soda is not used in any food in the UK, so you can’t get food grade caustic soda in the spice shelf (as you can in German supermarkets), and you can’t bring it in when coming back from holidays or get it mailed to you – Royal Mail and airlines consider it a dangerous substance, which is fair enough.

Most cookbooks in the UK recommend using baking soda instead for the alkaline bath. The problem is that while baking soda is slightly alkaline, an aquaeous solution will only reach a pH level of about 8.5 which is by far not strong enough to give pretzels the desired texture or taste. But here, a neat trick can help us out – if you heat baking soda, or sodium bicarbonate (NaHCO₃) above 80^oC, it will decompose into sodium carbonate (Na₂CO₃), CO₂ and water. And sodium carbonate is much more alkaline than baking soda, a solution can reach a pH level of about 11. Handily, the conversion can be done easily by baking 3-4 tablespoons of baking soda while preheating the oven. See e.g. here for a closer description of the chemical reaction.

⚠ A fair warning though: sodium carbonate and its solution are noticeably caustic! Be careful with it, make sure to not splash it into your face or eyes, and should you touch it, make sure you wash skin or fabrics with plenty of water right away. Some goggles or glasses would not be amiss! ⚠

⚠ Another warning: Do not use aluminium baking trays for this! Sodium hydroxide has some interesting reactions with the aluminium oxide layer protecting your baking sheet. This might lead to unusable powder (polluted with aluminium ions), a baking tray with holes in it and a hydrogen explosion in your oven. ⚠

The other issue I had with the first few tries of making pretzels is that they come out of their alkaline bath dripping wet, so if you put them on a baking tray like that, they will sit in the liquid and become a bit gooey, and the texture will be all wrong. I fixed this issue by putting a lightly oiled cooling rack on a backing tray, and thus baking the pretzels slightly suspended in the air – so the excess lye can drip off and not touch the pretzels anymore.

Ingredients:

• 350ml milk, lukewarm
• 10g fresh yeast
• 1/4 tsp of sugar
• 500g strong white bread flour
• 10g fine salt
• 3-4 tbsp baking soda
• 1.5l water
• coarse rock salt

Dissolve the yeast and the sugar in the milk, then add the flour and the fine salt and knead to get an elastic dough. Work it until not sticky anymore, then form into a ball on a slightly floured surface and rest for 1h.

Meanwhile, preheat the oven to 200^oC and use it to bake the baking soda on a tray for an hour or so. Be careful when retrieving it from the oven, it will now be noticeably caustic and can hurt skin, eyes, or fabrics!

After an hour, roll the dough into a tight ball again, and then separate into 12 equal pieces. Fold, and then roll out each piece into a string of about 40cm/16″ length, slightly thicker in the middle and thinner at the ends. Shape this into a pretzel and make sure the ends stick on the sides. Put it onto a floured kitchen towel (or a couche if you have one). Then repeat with the rest. Cover and let prove for another hour or so.

Bring the water to the boil in a pan that is wide enough for a pretzel. Prepare a baking tray with a lightly oiled baking or metal cooling rack on top. When the pretzels are done proving, carefully dissolve the baked baking soda in the boiling water.

Submerge one pretzel in the boiling lye and cook for about 20-30 seconds. Make sure it is properly submerged. Use a plastic tool for this! Then lift it out, place on the rack on the baking tray and scatter with coarse rock salt. Repeat with as many pretzels as fit on the rack. Then bake them for about 20-25 minutes until they are a dark, shimmering brown – it should remind you of a conker, not the dull brown of burnt toast. Then repeat with the next batch and so on.

Once cooled, they are ready to eat – either with just butter for breakfast, or with Obatzda and a beer in the evening… My little test eaters were very happy with the result!