• Step 1: In a large skillet, cook the diced bacon over medium heat until crispy. Remove the bacon from the pan, reserving the rendered fat.
• Step 2: In the same skillet, sear the beef cubes in the bacon fat over medium-high heat until browned on all sides, about 2-3 minutes per batch. Transfer the seared beef to a slow cooker.
• Step 3: Add the diced onion to the skillet and cook until softened, about 5 minutes. Add the garlic and cook for an additional minute, stirring constantly.
• Step 4: Deglaze the skillet with the red wine, scraping up any browned bits from the bottom of the pan. Bring the wine to a simmer and let it reduce by half, about 2-3 minutes.
• Step 5: Pour the red wine mixture into the slow cooker with the beef. Add the beef broth, tomato paste, bay leaf, thyme, rosemary, carrots, and mushrooms. Stir to combine.
• Step 6: Cover the slow cooker and cook on low for 7-8 hours or on high for 4-5 hours, until the beef is very tender.
• Step 7: In a small saucepan, melt the butter over medium heat. Whisk in the flour to create a roux. Cook, stirring constantly, for 2-3 minutes until the roux is lightly golden.
• Step 8: Slowly pour the roux into the slow cooker, stirring to incorporate. Cook for an additional 30 minutes on high, or until the stew has thickened to your desired consistency.
• Step 9: Season the stew with salt and pepper to taste. Sprinkle the reserved crispy bacon over the top before serving.