- Prepare the Ingredients: Start by slicing the onions, mincing the garlic, and chopping the bacon into small pieces. Slice the cremini mushrooms and set aside. Cut the chuck roast into bite-sized chunks and season generously with salt and black pepper. Rub the Dijon mustard evenly over the meat. 
- Sear the Meat: Heat a large skillet or the Instant Pot on the sauté setting. Add a bit of oil and sear the seasoned meat in batches until browned on all sides. This step adds depth of flavor to the dish by caramelizing the meat. 
- Sauté the Aromatics: In the same skillet or Instant Pot, add the bacon and cook until it begins to render its fat. Then, add the onions and garlic, cooking until softened and fragrant. 
- Combine Ingredients: Transfer the seared meat, onions, garlic, and bacon to the Instant Pot or slow cooker. Add the sliced mushrooms, bay leaves, Maggi seasoning, tomato paste, and beef stock. 
- Add the Beer: Pour the double bock beer over the meat and vegetables, ensuring they are fully submerged in the liquid. 
- Cook: If using an Instant Pot, seal the lid and set to manual high pressure for 60 minutes. For a slow cooker, cook on low heat for 6-8 hours or until the meat is tender and falling apart. 
- Adjust Seasoning: Once the cooking time is complete, taste the Bierfleisch and adjust the seasoning as needed with salt and pepper. 
- Serve: Serve the Bavarian Bierfleisch hot, garnished with fresh herbs if desired. Enjoy alongside your favorite sides such as mashed potatoes, spaetzle, or crusty bread.