Mix 150 ml of warm water with sugar and dry yeast. Set aside for 5 - 10 minutes or until the yeast becomes fluffy.
In a bowl mix the flour with the salt. Add the yeast mixture and the rest of the warm water and lemon juice. Stir with a spoon until the dough begins to take shape and set aside for a few minutes.
Add melted butter and begin to knead.
Knead the dough for 10 minutes until it becomes smooth and elastic. Then place it in a bowl, cover with plastic wrap and let rise in a warm place for 1 hour and a half or until it doubles in volume.
Deflate the dough. Knead briefly and divide it into 12 pieces similar to each other. Shape into balls and laid on a baking tray covered with parchment paper. Cover with a cotton cloth and let rise in a warm place for another hour.
Brush the rolls with a tablespoon of melted butter.
Bake in preheated oven at 180 degrees for 35 minutes. Once baked let them cool completely before serving.