Sprinkle the active dry yeast over the warm milk. Stir to dissolve it.
In a mixing bowl, stir together flour, sugar, and salt. Pour the hot water into the dry ingredients while mixing to distribute the hot water. Then, add the milk with dissolved yeast and egg and mix together until the dough is well combined and no more dry pockets remain. Round the dough into a ball, cover the dough, and let it rest for about 30 minutes to develop gluten.
Once the 30 minutes are up, punch the dough down and knead in the softened butter until all is absorbed. Knead the dough back into a ball, cover it, and let the dough proof until doubled, about 45 minutes to an hour.*If you prefer, you can knead the dough, either with a mixer or by hand, until the dough is supple and mostly smooth, knead in the butter, then cover and proof until doubled.*
When the dough has doubled, punch it down and knead it into a log, then divide the dough into 6 even pieces. Working with one piece of dough at a time, flatten each dough into an oval long enough to fit a hotdog and have about 1 inch extra flap on both ends. Lightly dust the surface and dough as needed.
Fold the ends of the dough over the hotdog then pinch the long sides of the dough together to seal the hotdog. Once sealed, roll the dough to make it more a more even cylinder and arrange them on parchment lined sheet pans.Using a scissor or knife, cut the sausage bread into 9-10 quarter inch slices. Make sure to cut all the way through the hotdog but NOT the bottom layer of dough. You want the dough to stay connected. Shape the sausage bread by placing the hotdog pieces left and right, alternately. Repeat with all. *Refer to post for picture reference.*
Cover the sausage breads and let the dough proof until 90% doubled, about 30-45 minutes.
Preheat the oven to 350°F.
For the corn and cheese topping:
In a bowl, combine the mozzarella, sweet corn, diced onion, green onion, and mayo. Mix until everything is well distributed. Set aside until needed.
Once the sausage bread is almost doubled, brush it with a thin layer of egg wash. Top each of the sausage breads with about 2-3 Tablespoons of the corn and cheese topping. Try to keep the toppings in the center of the bread and avoid the hotdogs if possible (mostly for aesthetics). Finally, sprinkle the breads with a couple dashes of dry parsley flakes if you wish.
Bake the sausage breads for about 20 minutes or until the bread is golden brown and the thickest part of the bread registers 190°F. Remove the bread from the oven and let it cool for for 10-15 minutes or until comfortable to handle.
Enjoy the Korean sausage bread warm, with or without a couple drizzle of ketchup!
*These Korean sausage breads are good for up to 1 week in the fridge if stored properly in an airtight container. They are best eaten warm, so feel free to heat it up in the microwave for 10-20 seconds or in the oven at 350F for 5-10 minutes.