Brown the calves' tails well on all sides in a pot with a bit of oil.
Then pour off the fat.
Add water so it completely covers.
Bring the tails to a boil and remove impurities.
Roughly chop the peeled onion and add it to the pot along with a bit of salt, thyme, and bay leaf.
Let the tails simmer for about 1 hour until tender.
Take them out and strain the bouillon through a cloth.
Pour it back into the pot and reduce it slightly if it lacks strength.
Then put the tails back into the bouillon and keep them warm.
Cut the root off the pointed cabbage and discard the outer leaves.
Cut the cabbage into rough pieces.
Divide the cauliflower into florets and cook them tender in salted water for about 2 minutes.
Cook the pointed cabbage in the last minute so it retains some crunchiness.
When serving, place the tails and cooked cabbage in a deep plate.
Pour the boiling bouillon over and serve the tails with slices of good bread.