Combine the beef, flour, salt, and pepper in a resealable plastic bag; shake to evenly coat the beef.

Heat the olive oil in a skillet over medium heat. Brown the beef in the olive oil. Transfer the meat into the bottom of a slow cooker and return the skillet to the heat. Add the sweet potato, potato, celery, turnip, and parsnip. Pour the vinegar into the hot skillet to deglaze the pan, scraping loose the particles from the bottom with a spatula; empty into the slow cooker. Return the skillet to the heat and melt the butter. Cook and stir the onion in the melted butter until softened; scrape into the slow cooker.

Combine the pineapple juice, Worcestershire sauce, brown sugar, garlic, beef bullion, and rum in a small saucepan; cook until the bouillon cube dissolves. Pour into the slow cooker.

Turn the slow cooker on to High; cook for 1 hour. Switch heat to Low and cook an additional 6 hours.