Dissolve the yeast in warm water (it has to be at room temperature or yeast won’t activate!)
In a bowl, mix the flour to salt and sugar and shape a wells.
Preheat oven to 50°C (122°F).
Dissolve the tomato concentrate in the yeast mix, pour in along with the olive oil, stir well using a spatula, then knead for 10mn until you get a uniform dough ball. Add a bit of olive oil if this seems too dry.
Turn off the oven but leave the light on (the high temperature will help your dough grow without cooking). Transfer the dough ball to the bowl, cover with a kitchen towel and leave to rest 1 hour.
Meanwhile, prep your wash. Blend the flax seeds (I’m using a coffee grinder). In a small bowl, stir in 3 tsp water and leave to rest for 15mn into fridge. Add in the mustard, maple syrup and milk. Set aside.
When the 1-hour resting time is over, oil your baking tray. Shape the dough into a perfectly round ball and lay in your tray, far enough from each other so they can keep growing without touching each other. Leave to rest for 45mn in the oven.
Take the tray out and increase your oven temperature to 200°C (392°C).
Brush your dough ball with the flax seeds based wash.
Bake for 15mn and leave to rest for 30mn before enjoying!