In the bowl of a stand mixer with the dough hook attachment, add the yeast, brown sugar and water and allow to stand for about 5 minutes until the mixture looks foamy.
Stir in the melted butter.
Stir in the flour and salt and knead on low speed with the dough hook for at least 5 minutes.
Turn the dough out onto a smooth surface and add a little more flour if it is too sticky. Form into a ball and place in an oiled bowl, turning the dough to coat. Allow the dough to rise for 60 minutes.
Preheat oven to 425 degrees.
Get pot of water heating on stove.
Punch down dough and divide into 16 equal pieces. Cut the Hillshire Farm® Polska Kielbasa into 16 equal pieces.
Flatten each piece of dough and place one piece of the Hillshire Farm® Polska Kielbasa into the center. Pinch the dough to seal and then roll into a ball in your hands until the dough is very well-sealed around the sausage piece. Repeat with each piece of sausage and dough.
Bring the pot of water to a boil and gently add the baking soda. Drop four stuffed pretzels at a time into the boiling water and cook for about 30 seconds. Take the stuffed pretzels out of the water with a slotted spoon and transfer to baking sheets lined with parchment paper.
Sprinkle the tops of the stuffed pretzels lightly with kosher salt.
Bake for 14-16 minutes, or until well-browned.