Combine the yeast and water in a large bowl/the bowl of a stand mixer. Let sit for 5 minutes to activate. Once it is bubbly/frothy it is ready (if it hasn't changed after 10 minutes, it may have expired - if so, start again!).
Once bubbly, add the melted butter, brown sugar and salt. Stir to combine.
Add in about 3/4 of the flour and bring together using a wooden spoon/a dough hook attachment on a stand mixer. If still wet, keep adding the flour until a slightly sticky dough has formed.
Either let the dough hook run for 3 minutes, or remove the dough onto a lightly floured surface and knead by hand for about 3 minutes. Let the dough rest in the bowl for 15 minutes.
Preheat the oven to 220C/180C Fan/Gas 7. Line 2 large baking trays (you will need to do this in batches).
Set up the baking soda bath by bringing 2 litres of water to the boil in a large saucepan, with the baking soda added. Let simmer while shaping the pretzels.
Remove the dough from the bowl (onto a lightly floured surface). Divide into 12 equal pieces of dough. Take one piece, roll into a long 30cm rope. Bring the two ends into the middle to create a loop. Twist these ends together and bring back onto the centre/top of the loop (see above for video link). Repeat for each piece.
Place these individual pretzels into the soda bath, lowering in using a slotted spoon. Remove after 10 seconds and place on the baking trays.
Combine the cinnamon and sugar and sprinkle over each of the pretzels. Bake for about 15 minutes (until really golden brown on top). Let cool on a wire rack before serving!