Mix warm milk, brown sugar, and yeast in a large container. Let it rest for around 15 minutes for yeast to activate.
When the yeast is active with bubbles on the surface, sift in the flour, then add 2 tablespoons of melted butter, salt, and the yeast-milk mixture. Knead by hand or use a stand mixer with a dough hook on Low speed for 5-6 minutes.
Brush the bottom of a stainless-steel or glass mixing bowl with some of the remaining melted butter. Place the dough in the bowl, turning it to coat all sides evenly. Cover with plastic wrap.
Place the bowl in a warm spot and let it proof until the dough is doubled. Alternatively, if you have an Omni Pro, place the bowl on the cooking pan at the proofing level. Touch Proof. Set oven temperature to 100°F / 38°C and set the time for 1 hour. Press Start. When the program ends, take the dough out.
Lay parchment paper on a large tray and on the cooking pan. Set aside.
Shape the dough into a log and cut it in half. Then, divide each half into four equal pieces, about 3 ounces each, for a total of 8 pieces.
Add water to a large pot and let it simmer on medium heat on the stove. Alternatively, you can add water to an Instant Pot pressure cooker and select Sauté function High for 30 minutes. When the bubbles start to come up, add baking soda to the water. Stir until the baking soda is dissolved.
Shape each piece of dough into a small log, then roll and stretch it with your palms into a 25-inch rope on a clean, flat surface. Avoid sprinkling flour on the surface.
Lift and bend the ends of the rope to make a U shape. Cross one end over the other twice to make a double twist in the middle. Fold down the ends and attach them to the bottom of the U to form a pretzel shape.
Once you shape the pretzels, transfer them to the large tray. Gently dip both sides of 4 of the pretzels into the simmering soda solution for 3 seconds. Take pretzels out of the water with the help of a skimming ladle. Place on the cooking pan. Sprinkle coarse salt or sesame on top of the pretzels.
Select the Bake function on your Omni. Set the temperature to 420°F / 215°C and set the time to 7 minutes. Press Start.
When the oven has preheated, place the cooking pan at the baking level.
When the pretzels are nicely browned, Cancel the program and take the tray out. Brush the tops of the pretzels with the remaining melted butter.
Repeat steps 10-13 for the remaining 4 pretzels. Let the pretzels rest for 10 minutes before serving.