1 Place the meat in the stewpot and cover with cold water. Bring to a boil, skimming.
2 Strain the meat and rinse out the stewpot.
3 Peel the carrots and onion. Slice the carrots and halve the onion.
4 Put the meat back into the stewpot with the carrots, onion and halved mushrooms, then cover with water.
5 Cook on medium heat for about 45 minutes.
6 Filter the cooking juices.
7 In a saucepan, make a roux by melting the butter, then adding the flour while whisking for 2 minutes.
8 Slowly add the cooking juices and then the sour cream.
9 Pour the sauce back on the meat and season.
Tip: for even smoother sauce, you can add 2 egg yolks along with the sour cream. Make sure not to boil the sauce after adding the yolks.v