Weigh out the flours and place in a bowl. It is best to grind the flaxseed, but you can also do without it. Add the grains and salt to the flour mixture and mix everything together.
Dissolve the yeast well in the lukewarm water.
Pour the vinegar into the flour mixture and pour in the yeast-water mixture and quickly mix everything well.
Then pour the dough into the cake tin and place in the cold oven. Do not let the dough rise! Set the clock to 60 minutes and switch on the oven: 200 ° with top-bottom heat. Never switch on the circulating air for gluten-free baked goods!
At the end of the baking time, take the pan out of the oven, take out the bread and bake again for 10 minutes at 180 °.