Warm large Dutch oven over medium heat. Once hot, add in coconut oil. If oil smokes, it is too hot. Once oil is hot, start browning meat on all sides. Brown meat in batches if necessary to prevent overcrowding the meat in the pot. Remove browned meat from pot and set aside on plate.
If pan is too dry, add a touch more coconut oil to the browned bits in pot. Add in onions and celery and sauté on medium heat for about 5 minutes until celery starts to get tender.
Add in garlic, rosemary leaves, and bay leaf and cook for one minute until fragrant. Season with salt and pepper.
Add meat back into pot with veggies. Pour in Guinness to deglaze the bottom of pot. Use a wooden spoon to scrape up any bits from bottom. This is where the flavor is!
Add in potatoes, mushrooms, and carrots. Pour in beef broth and stir to combine.
Bring stew to a boil. Cover with oven safe lid. Place Dutch oven in oven for 3 hours until meat is tender. Check halfway through cooking to ensure liquid level is still at least halfway up ingredients.
10. Remove from oven and let sit covered until ready to serve.