Prepare the dough:
In a bowl, add flour, instant yeast, sugar, salt and oil.
Start adding the lukewarm water gradually and knead well to form a dough. Keep kneading for 8-10 minutes.
Place the prepared dough in a greased bowl. Cover the bowl with plastic wrap and leave it in a warm and dry place to rise for approximately 1 hour.
Prepare the bun:
Once the dough has doubled in size, knead it back for a minute, and put it on a floured surface. Divide dough into 6 equal parts.
Take one part and roll it into a long strip of about 10-12 inches in length.
Wrap this strip around a sausage to cover it in a spiral form, make it taught and pinch the ends so that the dough will stick. Make sure a little bit of sausage is exposed in both sides when you wrap the dough.
Repeat step 3 with the rest of the dough and sausages.
In a big pot, add 5 cups of water and baking soda and bring it to a rolling boil.
When the water is boiling, drop the buns in the water and let it boil for 4-5 minutes. Keep lightly turning the buns while boiling to make sure it gets well boiled.
Lay the boiled buns on a greased tray covered with parchment paper. Whisk the egg yolk and brush it over the buns.
Add any topping you desire over the buns. I have sprinkled some pink salt along with some dried herbs.
Bake at 220°C for 15-20 minutes or until golden brown.