First prepare the broth: clean the vegetables, cut them into pieces and place them in a large pot.
Also add the flavourings, leaving only the soy sauce aside, cover with plenty of cold water and bring to the boil, then leave to cook for 1 hour.

While the broth is cooking, combine water and flour in a bowl and mix for at least 15 minutes, so as to activate the gluten mesh properly and until you obtain a smooth and homogeneous dough.
Then place it in a bowl and cover it with plenty of cold water.

Start the washing phase: massage the dough in the water, continuing until the water is whitish.
Drain the white water and cover the dough again, this time with hot water, then continue with the massages.
Continue alternating cold and hot water until the water is almost transparent even when you massage it, and finish the last wash with cold water.
Finally, give the dough a more elongated shape, as if it were a piece of roast meat.

Wrap the seitan in a clean cloth (without tightening too much), closing the ends with kitchen twine.
Add soy sauce and salt to the broth, immerse the seitan with all the cloth in the broth and leave to cook for 50 minutes, then leave to cool in the broth.

At this point you can lift the seitan from the broth, cut it into slices and use it.
Don’t throw away the broth as you will need it to preserve the seitan.

The homemade seitan is ready, all you have to do is store it in the fridge for up to 1 week, in an airtight container and covered with its cooking broth, waiting to use it for all your preparations.