In a large mixing bowl, combine warm water, sugar, and instant dry yeast. Let it froth for about 5 minutes.

Mix in melted unsalted butter and salt, then gradually add all-purpose flour. Stir until a rough dough forms and knead for 6-8 minutes.

Shape the dough into a ball and let it rise in a lightly oiled bowl, covered, for about 1 hour until doubled in size.

Punch down the dough, divide it into 8 pieces, and roll each into a log about 6 inches long.

In a large pot, bring water to a boil and add baking soda. Boil each log for 20-30 seconds, flipping halfway through.

Place the boiled logs on a parchment-lined baking sheet, brush with egg wash, and sprinkle with coarse sea salt.

Preheat the oven to 425°F and bake for 14-16 minutes until golden brown.

Cool the buns on a wire rack for about 10 minutes before slicing them open.