In a large bowl, dissolve the sugar in warm water, and then stir in yeast. Allow to proof until foamy (about 5 minutes).
Mix in egg, butter and salt.
Mix in flour one cup at a time.
Knead dough on a lightly floured surface until smooth (or use your bread hook/paddle on your kitchenmaid).
Place in a well oiled large bowl, and turn dough to coat. Cover with a damp cloth. Allow dough to rise until doubled in bulk, about 1 hour.
Shape into 8-10 balls. Place buns on greased baking sheet. Gently press down on each ball of dough to create a flat top. Allow to rise for 30-40 minutes.
Mix egg white and 2 Tbsp water together. Brush over rolls. Sprinkle with sesame seeds. (This step is optional)
Bake at 350 degrees for 20 minutes, or until golden brown. Rotate pan halfway through.
Brush buns with melted butter.