Combine flour, yeast, sugar and salt in a large mixing bowl. Add warm water and olive oil and mix until a shaggy dough forms. Continue to mix in a machine with a dough hook, or by hand for 8–10 minutes, until you can stretch a small portion of the dough into a thin membrane (this is called the “windowpane test”).
Place dough in a clean, oiled bowl, then cover and allow to rise until doubled in size, about 1 hour. Punch down the dough, cover and let rise another 30 minutes. Line a baking sheet with parchment paper.
Place dough on a lightly floured counter and shape into a 12-inch oval loaf. Place loaf on prepared pan, cover and let rise for 30 minutes, or until the dough gives with a gentle press of the fingers, leaving a faint indentation. Meanwhile, preheat oven to 400°F.
Whisk together egg and 1 tablespoon water. Brush the top and sides of the loaf with the egg wash, then sprinkle with sesame seeds, if using. Using a lame or sharp knife, make slashes across the top of the loaf, about 2 inches long and 1 ½ inches apart.
Bake for 20–25 minutes, until golden-brown and hollow sounding when tapped. The internal temperature should be between 180–200°F. Cool on a wire rack.
