Start by dissolving the yeast in a small bowl with a tablespoon of warm water. Let it sit for about 5 minutes until frothy.
In a large mixing bowl, cream together the butter and sugar until light and fluffy.
Add the beaten eggs, sour cream, and 2 teaspoons of vanilla extract to the butter and sugar mixture. Mix well.
In another bowl, combine the flour and the activated yeast mixture.
Gradually add the flour and yeast mixture to the wet ingredients, mixing until a soft dough forms. If the dough is too sticky, add a little more flour, one tablespoon at a time.
Turn the dough out onto a floured surface and knead gently for about 5 minutes until smooth.
Form the dough into a ball, place it in a greased bowl, and cover it with a clean kitchen towel. Let it rise in a warm place for about 1 hour, or until doubled in size.
Preheat your oven to 350°F (175°C). Punch down the dough and divide it into two equal portions.
Roll each portion into a rectangle about ¼-inch thick. Cut the dough into strips about 1 inch wide. Twist each strip and place them on a lined baking sheet.
Brush the tops of the twists with a mixture of the remaining 1 teaspoon of vanilla extract and a little melted butter for extra flavor.
Bake for 15-20 minutes, or until golden brown.
Once out of the oven, let the twists cool on a wire rack. Serve warm or at room temperature.