Put the water in a bowl and cool it 20s putting in the microwave. Pour yeast to re moisturize it. Leave on about 10min.
Put the flour, salt and sugar in a bowl. Add soft butter cut into small dices and mix for it to be absorbed. Then add the water with the yeast and mix until having a smooth dough that comes away from the walls. Let stand at least an hour.
Kneads the dough and form small balls about 5cm in diameter. Let stand at least 30 minutes.
Boil water with bicarboante. Dip each buns in it 30s and place on baking paper. Beat an egg and spread on buns for gilding. Make an “X” on top of the buns with a knife. Sprinkle the buns with coarse salt and bake 15 minutes at 200 ° C.