In the bowl of a stand mixer add the water and milk mixture, the sugars, and yeast and stir. Wait 5 minutes or until the yeast starts foaming.
Add half the flour and all of the starter to the bowl and mix on medium low speed until all is combined. Add the rest of the flour and mix until the dough pulls away from the sides. This dough will be slightly sticky however if it is still really sticky add flour a quarter cup at a time until the dough barely sticks to your hands.
Knead for 5 minutes until the dough is smooth and when you touch it the dough springs back.
Place in a bowl and cover for 10 minutes.
Preheat oven to 400°F or Gas Mark 6
While the dough is resting heat up the water and baking soda until it starts to form a rolling boil and reduce the heat to keep it boiling however not very hard.
Remove the dough from the bowl and slice into 8 equal portions. Place all but one portion back into the bowl and cover to keep from drying out.
Working one portion at a time roll into a long rope at least 24 inches and slice the rope into thirds. Twist each end into a knot and set on a silicon mat. Repeat with all eight portions.
Take your baking sheets near the stove. Working no more than 2-3 at a time drop the pretzels into the boiling water for 20-30 seconds. Using the skimmer remove from the water and shake a couple of times to remove excess water. Place them back on the mat and sprinkle the salt on the pretzels. Repeat until complete.