Pour the warmed milk into the bowl of a stand mixer. Sprinkle yeast over the milk.
Add the sourdough starter, oil, sugar, baking soda and half of the flour. Mix to combine.
Add salt and the rest of the flour. Attach dough hook and knead the dough for about 10 minutes. The dough should be slightly tacky to the touch.
If the dough is too wet, add additional flour 1 tablespoon at a time, but be careful not to add too much flour (see note.)
Transfer the dough to a large bowl sprayed with cooking spray. Cover the bowl and allow the dough to rise in a warm place for 30 minutes or until doubled in size.
Once doubled, punch down dough and divide into two loaves. Place them in greased loaf pans, cover and let rise again for another 20 minutes.
Preheat the oven to 400 degrees. Brush the tops of the loaves lightly with oil.
Bake loaves for 25 to 30 minutes. The top should be golden brown and the loaves should sound hollow when tapped. If using a thermometer, bread is done at 190 degrees.
Cool the loaves for 10 minutes in the pans and then remove to a wire rack to cool completely. Store in an airtight container.
Notes
In my experience, I needed to add close to 1 cup extra flour to get to the right consistency. If you need to add this much flour also add a bit more salt so that your dough is not bland.