Activate the Yeast: In a small bowl, combine warm water, yeast, and sugar (if using). Stir and let sit for 5–10 minutes until foamy.
Mix the Dough: In a large bowl, combine bread flour, whole wheat flour, and salt. Add the yeast mixture and mix until a dough forms.
Knead the Dough: Knead on a floured surface for 8–10 minutes until smooth and elastic.
First Rise: Place the dough in a greased bowl, cover, and let it rise in a warm place for 1–1.5 hours, or until doubled in size.
Shape the Loaf: Punch down the dough, shape it into a loaf, and place it in a greased or parchment-lined bread pan.
Second Rise: Let the dough rise again for 30–40 minutes until puffy.
Bake: Preheat the oven to 375°F (190°C) and bake for 25–30 minutes, until golden brown and hollow-sounding when tapped.
Cool & Serve: Let the bread cool completely on a wire rack before slicing.