Bring the water with baking soda to the boil and allow to cool.
Make a yeast dough from the remaining ingredients and knead in the food processor for a good 10 minutes. Let rest for 20 minutes, knead again briefly and shape into baguettes. Cover and let rise for about 1 hour.
Pour the lye into a shallow baking dish and dip the baguettes. Place on baking paper and cut deeply with a sharp knife. Place in the oven preheated to 250 degrees and steam vigorously. After 5 minutes steam again and set the oven to 210 degrees top and bottom heat.