Add cooking oil to Dutch oven set over medium-high heat and add cubed Chuck roast. Sear until browned on all sides, then remove and set aside.
Reduce the heat to medium and add the chopped onions (and more oil if needed), saute until tender, then add minced garlic and cook an additional 2 minutes. Remove garlic and onions from the pot and set aside.
Let pot cool slightly, reduce the heat to low and add butter. Once melted sprinkle flour over top to create a roux. Stir continually for 5 minutes, or until roux begins to darken in color.
Slowly add beer and beef stock to the roux, mixing to combine as it is added. Return beef, onions, and garlic to the pot and add all remaining ingredients except peas and parsley.
Simmer uncovered for 2 hours. Add peas and parsley in the final 5 minutes of cooking. Taste for salt and adjust as needed.
Serve alongside or on top of mashed potatoes.