Start by seasoning the stewing beef cubes with 2 teaspoons of coarse salt and 1/4 teaspoon black pepper. Heat 2 tablespoons of olive oil in a large Dutch oven over medium-high heat. Sear the beef in batches until browned on all sides, then transfer the browned beef to a plate and set aside.
In the same Dutch oven, add the chopped onion, carrots, celery, and minced garlic. Sauté over medium heat for about 5 minutes, stirring occasionally, until the vegetables are beginning to soften. Add 1 tablespoon of tomato paste and stir to coat the vegetables, scraping up any browned bits from the pot. I like to add the tomato paste at this stage because it really deepens the flavor and helps deglaze the pan.
Return the browned beef (from Step 1) to the pot with the sautéed vegetables (from Step 2). Pour in 3/4 cup red wine and 1 cup beef stock. Add the sprig of rosemary, 2 bay leaves, and 1/4 teaspoon dried thyme. Increase the heat and bring the stew to a boil, then reduce the heat to low, cover the pot, and let it simmer gently for about 1.5 hours, or until the beef is tender and the flavors meld together.
Once the beef is tender, in a small bowl, whisk together 2 tablespoons flour and 1/4 cup water until smooth. Increase the heat to medium and stir this mixture into the simmering stew. Cook for a few more minutes until the sauce has thickened. For a silky sauce, I make sure to whisk the flour and water really well before adding—it prevents lumps.
Taste the stew and adjust seasoning with more salt or pepper if needed. Remove the bay leaves and rosemary sprig before serving. Serve the stew warm and enjoy the rich, hearty flavors.