Heat the olive oil in a large Dutch oven over medium-high heat. Add the beef and season with salt and pepper. Brown the meat on all sides, then remove it to a plate.
Add the mushrooms, pearl onions, and carrots to the pot. Cook for 5 minutes until the mushrooms release liquid and the onions start to soften. Stir in the garlic and cook for 1 minute more.
Stir in the tomato paste and cook for 2 minutes. Pour in the red wine and scrape the bottom of the pot to release any browned bits.
Return the beef to the pot along with the lentils, beef broth, thyme, and bay leaves. Bring the mixture to a boil, then reduce to a simmer.
Cover and cook for 45 to 60 minutes, stirring occasionally, until the beef is tender and the lentils are soft. Remove the thyme sprigs and bay leaves before serving. Taste and adjust salt and pepper as needed.