All ingredients need to be at room temperature.
Activate the yeast, mix it with 3 1/3 tbsp (50 ml) of the preheated milk, 1 tbsp sugar and 1 tbsp flour, until you get a thick mixture. Leave it to bubble. In the meantime, sift the flour in a large container and mix it with the sugar.
Make a well, pour in the eggs, which you've beaten lightly with a fork, plus the sour cream, pinch of salt, orange zest, essence, milk, softened or melted butter and finally the effervescent yeast. Knead a soft, nonstick dough.
Leave it in an oiled container, cover with a towel and leave it to double in volume.
Shape the risen dough very carefully into the desired form. Place it in an oiled and generously floured form. Mine was 10 1/4″ (26 cm) in diameter. Leave it to rise. You can also place it in the oven at 122°F (50 °C).
Turn the oven up to 320°F (160 °C) and bake until ready.