In the bowl of an electric stand mixer fitted with a paddle attachment add the hot water, sugar, butter, and salt. Mix to combine and let cool to luke warm.
Add the starter and 1 cup of flour. Mix until smooth.
Add the egg and mix until combined.
Change to the paddle attachment and gradually add enough flour to make a soft dough.
Move the dough to a large oiled bowl and cover with plastic wrap. Set in a warm area free of drafts and let rise until doubled, approximately 90 minutes.
Divide the dough into 12 pieces and then divide each piece into 3. Roll into balls and place 3 balls into the cavity of a muffin tin, seam-side down. Cover with plastic wrap and let rise for 1 hour.
Remove the plastic wrap and bake at 350 °F for 20 minutes.
Remove from the oven and brush the tops with melted butter and coarse salt if desired.
Notes
Once you're ready to divide the dough, don't incorporate flour into the pieces or the dough balls won't stick together while baking.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.