Start by dusting the beef pieces with flour, salt, and pepper. Shake off the excess and set it aside.
Heat two tablespoons of olive oil on medium-high heat in a deep pot.
Add the dusted beef pieces to the pot and cook until all sides of the beef pieces are browned.
Remove the beef and set aside.
Add the remaining olive oil to the pot and start sautéing the onions until translucent.
Toss in the garlic and cook until fragrant.
Add tomato paste, rosemary, bay leaves, and sage to the pot and let them cook for a minute.
Throw the browned beef into the pot and stir everything.
Deglaze the pot with red wine and let it simmer for 5 minutes.
Next, pour the beef stock and water into the pot.
Lightly season with salt and pepper.
Cover the pot with a lid and let it simmer on medium-low for 1 ½ hour to 2 hours or until the meat is almost tender.
Add the potatoes, mushrooms, and carrots to the pot and let them cook until meat and vegetables are tender (about 15 to 30 minutes).
Finally, serve the beef spezzatino hot along with crusty bread on the side.