Heat a tablespoon of olive oil in a large Dutch oven (or stockpot) over medium-high heat. Toss the meat into a bag with flour, paprika, garlic powder, sea salt, and freshly cracked pepper, to taste. Toss to coat evenly.
Add half of the stew meat and onion to the pot, then cook for about 2-3 minutes. Remove the beef and set it on a plate. Add the remaining meat and onion to the pot, then cook for about 2-3 minutes, until browned. Add the first batch of beef and onions, along with their juices, back to the Dutch oven.
Add the minced garlic and cook for 30 seconds.
Deglaze the pan with the red wine, scraping the bits off the bottom of the pot, for 2 minutes.
Add the diced tomatoes, fresh thyme sprigs, and bay leaves along with the stock.
Cover and place in the oven to slow cook for at least 4 hours.
After four hours, remove the Dutch oven from the oven and place it on the stovetop over medium-low heat.
Add the remaining tablespoon of olive oil to a large skillet over medium heat. Add the mushrooms and cook, stirring occasionally, for 2 minutes.
Add the carrots and celery to the pan and cook for 2 minutes, stirring often.
Add the vegetables to the stew along with the potatoes. Cover and cook on low for 60-90 minutes, making sure to spoon off any fat that settles on the surface every 30 minutes.
Combine the remaining ½ cup of cold beef stock with the cornstarch to make a slurry, mixing until well combined with no lumps.
Pour the slurry into the stew while it’s boiling, stir, then reduce the heat to low. Taste, and season with sea salt and freshly cracked pepper, to taste. Serve and enjoy!