Bring a pot of salted water to boil. Meanwhile, grate raw potatoes on the fine holes. Add flour, egg, and salt and mix.
Use a halušky maker, or spaetzle maker, to drop the dough into the boiling water.
If making bryndza alternative, blend ingredients until smooth. What proportions? You can make it as strong or mild to suite your taste – more feta will make it stronger, sour cream will make it milder; cream cheese will be thicker, sour cream thinner. To start with, try half a cup of each feta and sour cream and 1½ tbsp butter.