Combine the wine, bay leaf, black pepper, chopped garlic, and mixed herbs in a bowl. Cut the beef into roughly 2cm pieces, add to the marinade, cover, and refrigerate for 12 hours (overnight).
Remove beef from marinade and pat dry. Strain and reserve the marinade. Heat the oil in a large pot over medium-high heat and brown the beef on all sides, about 10 minutes. Add the cognac, let simmer for 1-2 minutes, then pour in the strained marinade and add the chopped onions. Cover and simmer on medium-low heat for 1.5 hours until the beef is very tender and reaches 63°C/145°F internally.
Fry the mushrooms over medium heat until golden, about 3-4 minutes. About 10 minutes before the braising time is complete, add the mushrooms to the pot and continue simmering.
Season with salt and pepper to taste. If the sauce is too thin, stir in the sauce thickener according to package directions and simmer for 1-2 minutes until thickened to your preference.