Preheat the oven to 50°C and switch off as soon as it is warm. The bread dough can rest here later.
Put lukewarm water in a bowl and crumble in fresh yeast. Add maple syrup and stir with a non-metallic (such as wooden or plastic) spoon. Let the mixture sit for 10 minutes until small bubbles form on the surface. Mix in the ground flea seeds, linseed and apple cider vinegar and leave to rest for another 5 minutes.
In a large bowl mix all dry ingredients. Add the yeast starter and mix thoroughly with a plastic or wooden spoon. Cover with a clean kitchen towel and let rest in the warm oven for 1 hour. During this time, the dough should rise to about twice its size.
Line a 1.5 l loaf tin with baking paper. Fill in the dough, cover with the kitchen towel and let it rise for 15 minutes.
In the meantime, preheat the oven to 220 °C top and bottom heat.
Bake the bread for 45 minutes. Take the loaf tin out of the oven, pull the bread out of the tin using the baking paper and put it back into the oven without the tin (including the baking paper) and bake for another 30 minutes.
Take the bread out of the oven and let it cool completely.