Cut steak into 1-inch pieces.
Toss with flour, salt, and pepper.
Heat olive oil and butter in large saucepan and cook steak, in batches, until browned, about 5 to 6 minutes per batch. When all the beef is browned, remove from pan and set aside.
Cook onions and garlic in the drippings remaining in saucepan, stirring to scrape up drippings, about 3 minutes.
Place onion mixture in 4-quart slow cooker along with beef, beer, thyme, carrots, and Stock.
Cover and cook on low for 8–9 hours or until vegetables are tender.
Add potato flakes and egg noodles, turn heat to high, and cook for 10–12 minutes or until noodles are tender and stew is thick. Stir and serve.