Heat 180g water to between 38-46°C (100-115°F) in a small saucepan.
Pour the warm water into a small-sized glass bowl. Stir in the yeast and brown sugar. Let the mixture rest for 10-20 minutes until the surface becomes thick and bubbly.
Whisk the psyllium husk and flaxseed together in a medium sized bowl. Stir in 320g of water (straight from the tap is fine), then allow the mixture to stand for 5 minutes until a thick gel forms.
In a large mixing bowl or the bowl of a stand mixer, whisk together the buckwheat flour, teff flour, chickpea flour, tapioca starch, and salt.
Add the yeast mixture, psyllium and flaxseed gel, black treacle, apple cider vinegar and olive oil to the flour mix.
Mix all these ingredients together for about 5 minutes until the dough is well combined but still slightly sticky to the touch.
Dust your hands with extra tapioca starch and scrape the dough out of the mixer and place it on a clean work surface. Roll and shape the dough into a smooth log shape.
Carefully place the shaped dough into a lightly greased 3lb loaf tin, making sure the surface is nice and smooth and has an even shape in the tin. Cover the tin with cling film (plastic wrap) or a clean cloth.
Place the tin somewhere warm and damp to prove for 1 hour (see notes on proving).
After 50 minutes of proving, preheat the oven to 200°C / 180°C fan assisted / gas mark 6 / 400°F.
Once the dough has been proving for an hour and has risen by about ⅓ (just reaching the top of the tin) then it’s ready to bake.
Before placing in the oven, brush the top of the loaf with the olive oil and scatter with buckwheat flakes, pressing them slightly as otherwise they don’t stick.
Place the loaf on the centre shelf of the oven and bake for 15 minutes at 200°C / 180°C fan assisted / gas mark 6 / 400°F.
After 15 minutes turn the temperature down to 180°C / 160°C fan assisted / gas mark 4 / 350°F and bake for 45 minutes.
Take the bread out of the oven and immediately remove it from the tin. Turn it out onto a wire rack to cool completely before cutting.