Whisk active starter, lukewarm milk, honey, melted butter, and egg together in a mixer bowl.

Add bread flour and salt, kneading with dough hook for 8 minutes until satiny.

Cover dough and let rise at room temperature for 4 to 6 hours until puffy.

Divide dough into 12 equal rolls and place in a greased 9x13-inch baking pan.

Let rolls rise for 2 hours until doubled and touching.

Heat oven to 375 degrees Fahrenheit and bake rolls 22 to 25 minutes until golden.

Brush hot rolls with melted butter and sprinkle flaky sea salt.