In a large bowl, mix together the lean ground beef, breadcrumbs, egg and ½ of the sauce. Season to taste with sea salt and fresh pepper. Pat the mixture into the loaf pan and bake for about 45 minutes. Remove from the oven, and spread the remaining sauce over the top. Bake for another 5 minutes. The internal temperature of the meatloaf should be around 160 degrees. Let rest before slicing.