Trim the filet mignon.
Chop the onion.
In a saucepan, sauté the seasoned filet over high heat, then
lower the heat and cook for 5 minutes.
Remove the filet mignon, add the mushrooms cut in 2 or 4
depending on their size.
Cook the mushrooms with the chopped onion for 1 minute
then put the filet mignon back in the pan.
Deglaze with St-Rémy® Brandy, add the cream and thyme sprig.
Cook covered for 8 minutes.
Serve directly in cocotte.