Warm the milk to between 100-115 F / 38-46°C . Then pour into a medium sized glass bowl and stir in the yeast and brown sugar. Rest for 10 minutes until the surface is looking thick and bubbly.
Stir the water and psyllium husk together in a medium sized bowl until combined. Allow to stand for 2-4 minutes until it forms a gel.
Whisk the sorghum flour together with the potato starch, tapioca starch, ground ginger and salt in a large mixing bowl or a stand mixer.
Add the yeast and milk mixture, psyllium gel, apple cider vinegar, cooled melted butter and egg whites.
Beat together for about 5 minutes until the dough is well combined but still a little sticky to the touch.
Dust hands with extra tapioca starch and scrape the dough out of the mixer.
Place on a work surface and roll and shape the dough together into a smooth log shape.
Place the dough carefully into a lightly greased 3lb loaf tin.
Place the tin somewhere damp and warm to prove for 1 hour (see notes on proving).
After the dough has been proving for 50 minutes turn the oven onto 190°C /170°C fan assisted oven / gas mark 5.
Melt the butter for brushing over the top of the loaf.
Once the dough has been proving for an hour it should have risen by ⅓, just reaching the top of the tin. Brush the surface with the melted butter then place in the oven to bake for 50 minutes. The loaf is baked when golden brown.
Remove from the oven and take the bread out of the tin straightaway to cool on a wire rack. Allow to cool completely before cutting.