Pat the beef cubes dry with a paper towel. In a mixing bowl, toss the beef with flour, salt, and pepper until evenly coated.

Heat olive oil in a large skillet over medium-high heat. Add the beef in a single layer (work in batches if needed) and sear until browned on all sides, about 2-3 minutes per side. Transfer the seared beef to the basin of a 6-quart or larger slow cooker.

Reduce the skillet heat to medium. Add the chopped onion and cook until softened, about 5 minutes. Add the minced garlic and cook for 1 more minute until fragrant.

Pour the red wine into the skillet to deglaze, scraping up any browned bits from the bottom. Allow it to simmer and reduce by half.

Stir in the tomato paste and cook for 1 minute. Transfer the onion mixture to the slow cooker.

Add the beef broth, crushed tomatoes, dried oregano, and dried rosemary to the slow cooker. Stir to combine.

Cover and cook on low for 7-8 hours or on high for 4-5 hours, until the beef is tender.

In the last 30 minutes of cooking, stir in the drained artichoke hearts and Kalamata olives.

Serve hot, garnished with crumbled feta cheese and fresh parsley.