In a larger bowl or mixer with hook attachment.
Add flour and salt - mix to combine.
Pour in the yeast mixture.
Mix on medium speed scraping the sides of the bowl as needed.
Once all the flour is mixed in - knead for 2 minutes on medium-low speed (or with your hands for 5 minutes).
This is a soft dough so do not be tempted to add more flour.
Then add the soft butter.
Knead for 3 minutes more on medium speed.
By this time the dough will still be soft and elastic but less sticky and shinier.
Place the dough in an oiled bowl, cover and let rise until double in volume for about 45 minutes.