Combine warm water, sugar and yeast in a large bowl or the bowl of your stand mixer. Mix together and set aside for 4 minutes or until it begins to bubble.
Add, salt, melted butter, and two cups of flour a cup at a time mixing with a spatula or wooden spoon in between.
Attach dough hook to your stand mixer (or electric hand mixer). Add the remaining flour a cup at a time while mixing on a medium speed. Mix for about 3 minutes or until the dough comes together and bounces back when pressed lightly with your clean finger. If your dough is still quite sticky you can mix in a ¼ cup of flour.
Transfer to a lightly floured counter and knead for about 4 minutes or until smooth and bouncy.
Important note - See my tips section below on how to do the windowpane test if you are unsure whether your dough has been kneaded enough or not.
Transfer dough to a large, lightly oiled bowl then cover with plastic and place in a warm place to rise for 40 minutes or until roughly doubled in size.
Divide dough into 8 pieces then roll into 20-24 inch ropes. Form a U shape with the dough then twist the two ends together at the top leaving about an inch and a half free. Loop the twisted portion down to form a pretzel shape. Repeat for the remaining ropes.
Preheat oven to 450F
Line two baking sheets with parchment paper or silicone mats. Bring 10 cups of water and the baking soda to a rolling boil then add the pretzels in one at a time for 30 seconds, remove with a slotted spoon, and place on your lined baking sheet.
Brush with the beaten egg and a teaspoon of water then sprinkle with coarse salt. Bake for about 12 minutes or until golden brown.