Combine water, sugar, and yeast in a large mixing bowl. Let sit for 5 minutes until foamy. Stir in butter and salt, then slowly add flour.

Use the dough hook of a mixer or your hands to knead the dough for at least 5 minutes. The dough should be elastic and pull away from the bowl.

Cover the bowl with a damp towel and set in a warm place to rise until doubled, about an hour.

While dough is rising, sear steak quickly in a large skillet over high heat.

Remove steak from pan, lower heat to medium, and add onion. Stir occasionally as onion browns; when onion is translucent, add whiskey. Continue cooking until onion caramelizes to golden brown.

Add mushrooms to the skillet and cook for 8-10 minutes until mostly cooked through.

Remove skillet from heat and add steak back to skillet. Stir in pub cheese and set aside.

Preheat oven to 400º and line a baking sheet with parchment paper.

Combine water and baking soda in a large pot and bring to a rolling boil.

Use a slotted spoon or spatula to gently lower one calzone into the boiling water. Cook for about 20 seconds on each side and set on prepared baking sheet, then repeat for remaining calzones.

Whisk egg yolk and water together and brush over calzones. Sprinkle generously with coarse salt.

Bake at 400º for 15-20 minutes until golden brown. Let sit for 5-10 minutes before serving.