Lightly grease a 9x5-inch microwave-safe loaf pan and sprinkle with cornmeal.

Pour water into a large bowl. Add yeast and stir to dissolve. Add milk, sugar, salt, and baking soda, then add whole wheat flour; beat until well combined. Beat in all-purpose flour, 1/2 cup at a time, until a soft dough forms.

Turn dough out onto a lightly floured surface and knead until smooth, about 5 minutes. Shape dough into a loaf and place into the prepared pan.

Cook, uncovered, in a 650-watt microwave oven set at 50% power for 1 minute. Let rest for 10 minutes.

Repeat Step 4 one or two times, until loaf has doubled in size.

Microwave on high until top of loaf is no longer moist, 4 to 6 minutes.