Warm the milk (to 110 degrees F); add to the bowl with butter, sugar, and sourdough starter. Mix.
Add the flour and mix well until the dough forms a soft ball. Turn out onto a lightly floured counter and knead for 3 minutes. Then form the dough into a smooth ball of dough and place into a lightly-oiled bowl.
Cover with plastic wrap and allow to rest/rise for 2 hours.
Once the dough has risen, turn out onto a lightly floured counter. Punch the dough down and knead lightly for a brief minute or two. Then separate the dough into 12 equal pieces.
Roll out each piece into a long strip 26-30" in length. If you are slow to roll out the pieces, then cover the balls of dough with a damp cloth to prevent them from drying out.
Once the dough strips have been rolled out, shape them into a pretzel and place them on a parchment-lined cookie sheet. You will need to use 2-3 cookie sheets.
Place the cookie sheets in the freezer for 20-30 minutes. The goal is to allow the pretzels to harden just enough that they can be dunked in the water bath. Pretzels can be frozen up to a couple weeks if they are airtight in the freezer. Freeze them on the pan and then re-wrap them if you plan to freeze longer.
With the pretzels in the freezer, preheat the oven to 450°F. Fill a large gallon stockpot with about 12 cups of water and bring to a strong simmer. Add 2-3 tbsp baking soda and allow to dissolve.
Remove the pretzels from the freezer; add them to the water (2 at a time), and allow to simmer until they float to the top. Gently remove from their bath and place back on the parchment paper on the cookie sheet.- only takes about a minute or less to float.
Brush with coconut oil and sprinkle with your choice of toppings. Bake at 450°F for 14-15 minutes until lightly brown. The color will partly depend on how much baking soda is in your water.
Remove and allow to cool before enjoying.