For the dough:
For the Soda water:
In a large bowl, mix the flour, yeast, sugar, salt, butter and milk. Mix until well combined.
Knead until the dough is smooth and soft.
Cover the dough and let it raise in a warm place for 2 hours.
Knead the dough one more time to remove all the air bubbles that formed during the rising period.
Divide the dough into equal pieces (from 80 to 85 gr each one) . Roll each dough piece and form a pretzel.
Repeat the process with the rest of the dough.
Lay the pretzels in a lined baking tray, cover and let them rest for 30 minutes (or until it's double in size).
While the pretzels are resting, prepare the soda water. Do this by combining the baking soda, water and salt in a wide pot.
Bring it to a boil, then remove from the heat.
Drop each pretzel in the hot soda water.
As soon as it rises to the surface, remove (with a slotted spoon) it from the soda water and place it back on the baking tray.
Let them rest for 30 minutes.
Sprinkle the pretzels with the coarse salt and bake on a previously pre-heated oven at 180°C for 20 minutes or until golden brown.