Stir yeast into warm water in a small bowl and set aside to proof while you gather other ingredients.
Mix together sugar, salt, eggs and sour cream in a large bowl. Add yeast mixture. Add flour to mixture using a spatula to incorporate, making a soft, moist dough. Cover and let rise until double (around 1 1/2 hours)
Turn dough out on to a floured surface. Dust with flour as needed to enable you to roll out the dough. Roll the dough into a rectangle (this is for a large cake - if you would like 2 smaller cakes, cut the dough in 2). Spread filling on the dough leaving a little space on the edges. Roll the dough (starting from the long end) and form the dough into a ring, pinching together the seams and the edges.
Let the formed dough rise for until double - about 1 hour.
Bake at 350 degrees for 13 to 15 minutes.
Let the cake cool. Mix together the powdered sugar with enough milk to create a spreadable glaze. Add lemon extract to the glaze. Spread the glaze on the cake and sprinkle with the colored sugars.
The filling for this cake is traditionally a cinnamon and sugar mixture. For that filling, spread softened butter on the rolled out dough and sprinkle with cinnamon sugar.
I filled the cake with a cream cheese mixture which was 8 oz. softened cream cheese and 1/2 brown sugar combined.
You can fill this cake with whatever you like. You might try an apple pie filling or a praline filling. I've seen cakes with a banana filling and a caramel glaze. So many possibilities . . .
One note: It is best to plan ahead. Get your ingredients out early and bring everything to room temperature before you begin. Make sure the butter and shortening are soft so they will incorporate easily into the dough.