In a medium bowl, stir together the warm water, yeast, and sugar until the yeast and sugar are dissolved. Allow it to sit for about 5 minutes. The yeast will be foamy or bubbly.
In the bowl of a stand mixer fitted with a dough hook, add the sea salt, flour, oil, and melted butter and turn on low speed. Gradually add the water-yeast mixture. Increase the mixer speed to medium and mix until the dough is smooth and pulls away from the sides of the bowl, about 2 minutes. If there are dry ingredients left in bowl, add a tablespoon of water at a time until all the flour is well incorporated.
Grease a medium glass bowl. Transfer dough to bowl, coating in oil. Cover with a tea towel and place to rise until the dough doubles in size, about 1 hour. Preheat the oven to 375 degrees.
Punch down the dough and turn it out onto a lightly floured surface. With floured hands, divide the dough into two equal portions.
Grease two 9 x 5 inch loaf pans with cooking spray. Shape each half into a loaf and place into prepared pan. Cover pans with a tea towel and let rest 20 minutes for a second rise.
Bake the loaves until golden brown, 20 to 25 minutes.
Remove the bread from the oven and turn it out onto a cooling rack. Brush the tops with melted butter. Cool for at least 10 minutes before slicing.