Preheat the oven to 200C/400F/Gas 6. Sift a tablespoon of white flour over large baking tray.
Put the white and wholemeal flour in a large bowl and stir in the sugar, bicarbonate of soda and sea salt. Tip onto a clean work surface and scoop into a heap. Make a well in the centre.
Mix the yogurt and milk in a large jug until smooth. Pour roughly a fifth of the milk mixture into the well and mix some of the flour into the liquid with a wooden spoon. Add a little more and continue to draw the flour into the liquid. If you have a massive mixing bowl, you can do the mixing in there instead. Keep adding and mixing until all the liquid and flour is combined.
Using your hands, knead the dough for a couple of minutes, or until light and spongy. You may need to add a little extra flour if the dough is sticky, but try not to add too much as you want the bread to be light and airy.
Divide the dough into six portions (or nine if making dinner rolls) and roll into balls. Place on the floured baking tray, evenly spaced apart. Flatten slightly with the palm of your hand until around 4cm/1½in deep.
Brush the rolls with a little milk and bake for 25-35 minutes, or until well risen and golden-brown. The crusts should be nice and crisp and the bottom of each roll should sound hollow when tapped. Larger rolls will take longer to cook. Transfer to a wire rack and leave to cool or serve warm.