In a large bowl, combine warm water and yeast, stirring until slightly dissolved.
Add yogurt, white flour, whole wheat flour, and salt.
Mix with a wooden spoon or hands until a rough dough forms.
Cover and let rest for 1 hour to hydrate.
Turn the dough onto a lightly floured surface and knead for 5 minutes until smooth and elastic.
Place back in the bowl, cover, and let ferment until doubled in size—about 3–6 hours (warmer = faster, cooler = slower).
While waiting, grease or line a loaf pan with parchment paper.
Once doubled, shape the dough into an oval sandwich loaf.
Place it in the prepared loaf pan and let it rise until slightly puffed over the edge—about 1 hour, depending on temperature.
Same-Day Bake: Preheat oven to 450°F (232°C) while the dough continues to rise.
Overnight Ferment: Cover and place in the fridge overnight for deeper flavour. Bake within 24 hours (no need to bring to room temp).
Optional: Lightly flour and score the top before baking.
Place in the oven and immediately lower temperature to 375°F (190°C).
Bake for 30–35 minutes, until golden brown and the loaf sounds hollow when tapped on the bottom.
Let the bread cool completely before slicing for the best texture.