Dice the bacon, carrot, celery, onion and leek as small as possible. Heat the olive oil and sweat everything together with the thyme. Add the lentils, deglaze with Madeira and port and let it boil down a little. Then fill up with the vegetable stock and let everything simmer for about 40 minutes. Puree finely with the hand blender and pass through a sieve. Bring the soup to the boil again and add the cream. Season to taste with salt, pepper and aceto. Foam the lentil soup again with the hand blender and gradually add the cold butter. Transfer to deep plates and serve.
Tip: Garnish with salmon or ham and fine diced vegetables sweated in butter.