In the bowl of a stand mixer fitted with the dough hook, combine the yeast, lukewarm water (105–110°F), and brown sugar. Let sit about 5 minutes until the mixture becomes foamy.

While the yeast proofs, melt 4 tablespoons of butter in the microwave, stir in the milk, and set the mixture aside to cool slightly.

Add the milk–butter mixture to the yeast and mix briefly on low speed with the dough hook until combined.

Add the fine sea salt and the flour, then mix with the dough hook until the flour is fully incorporated into the dough.

Knead the dough in the mixer on medium-high until it forms a slightly tacky but firm ball; if it is overly sticky, add extra flour one tablespoon at a time until manageable.

Lightly oil a large bowl, place the dough inside, cover with a damp towel, and let it rise in a warm spot until doubled in size, about 1 hour.

Preheat the oven to 400°F. In a large pot, bring 4 quarts of water to a rolling boil; carefully add the baking soda a little at a time—the mixture will bubble vigorously.

Punch down the risen dough to release air, then divide it into eight equal pieces (each piece is approximately 100 g).

Roll each piece into an 8–10 inch rope and wrap it around a hot dog, pinching or tucking the ends to seal the dough.

Working two at a time, gently lower the dough-wrapped hot dogs into the boiling baking-soda water; boil for 60–90 seconds per side, turning once so both sides are submerged. Remove, drain, and place on an oiled baking sheet.

Immediately sprinkle coarse sea salt over each pretzel dog to taste. Repeat with the remaining wrapped hot dogs. Do not let them rest—transfer straight from the bath to the oven.

Bake for 22–25 minutes, rotating the baking sheet once, until the pretzel dogs develop a deep, mahogany-brown crust.

As soon as they come out of the oven, brush each pretzel dog with the remaining 2 tablespoons of melted butter to ensure a soft, glossy crust.

Serve warm with your favorite condiments, or cool completely and freeze for later use.