Melt butter over high heat in a large Dutch oven or pot.
Add half of the Beef Stew Meat so the pot isn't crowded. Cook until browned on all sides. Repeat with the second half.
When all the beef is browned, place it all back into the pot. Stir in the flour. Cook for 2 more minutes.
Add the potatoes, onion, celery, carrots, parsnips, and garlic.
Add the thyme sprigs and the salt and pepper.
Pour in the beer and the water.
Bring to a simmer over medium heat, reduce heat to low, and simmer until the beef and vegetables are tender, about 2 hours.
Stir in fresh parsley before serving.
You can use beef Stew Meat or cut your own beef chunks from any cut of roast. I used baby potatoes because they keep their shape best during the long cooking time. You can also use diced red potatoes or leave them out and serve the Irish Beef Stew over mashed potatoes.