For the dough mix flour, 2 teaspoons salt and sugar. Crumble yeast over it. Add 50 g butter and about 300 ml lukewarm water. Knead everything smooth with the dough hooks of the mixer for about 10 minutes. Cover and leave to rise in a warm place for about 1 hour.
Knead dough on some flour and divide into 8 pieces. Roll each piece into a strand (approx. 30 cm long), fold in the middle and twist into a cord. Form the twisted strand into a knot and place it on a baking tray lined with baking paper. Cover and leave to rise for another 15 minutes.
Bring approx. 1 l water, baking soda and 1 teaspoon salt to the boil in a small pot. Put the knots one by one with the upper side into the lye and let it soak for about 30 seconds. Turn around and let it stand for another 10 seconds. Lift out with a skimmer, drain well and place on the baking paper. Spread all the knots with milk and sprinkle with sea salt, caraway and poppy seeds if desired. Bake in a preheated oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer) for approx. 15 minutes.