Prepare your ingredients, such as cut beef into cubes and slice vegetables.
Heat the oil in a large Dutch oven or large pot over medium-high heat. Saute the beef and onions for 3-5 minutes until the onion are soft. Add garlic. Season with salt and pepper. Continue cooking until beef is browned.
Add the carrots, celery, lentils, tomatoes, beef stock, bay leaves, thyme, 1 teaspoon salt, and cayenne pepper.
Bring to a boil. cover, reduce heat, and simmer, for about 60-75 minutes until the beef and lentils are tender. Remove the bay leaves and stir in the tarragon Add salt and pepper to taste.