Place flour, salt and pepper in a large zip-top bag. Add the cubes of beef, seal the bag, and shake to coat the meat with the flour mixture. (Alternatively, you can place the beef, flour, salt and pepper in a large bowl and stir to coat the beef.)
Heat 1 ½ tablespoons of the olive oil in a large skillet or Dutch oven over medium heat. Add the pieces of beef in a single layer in the pan (brown the beef in two batches if necessary). Let the beef brown on the first side for about 4 minutes, then flip and brown the other side. Stir in any remaining flour from the bag and then transfer the beef to the slow cooker.
Add the remaining ½ tablespoon olive oil and the onion to the pan. Cook the onion, stirring occasionally, until softened, 3-4 minutes.
Add the garlic and cook, stirring, for 30 seconds.
Pour about ½ cup of the beef broth into the pan and scrape up any browned bits from the bottom of the pan. Transfer the contents of the pan to the slow cooker.
Add the remaining ingredients, including the rest of the broth, to the slow cooker. Stir gently to combine.
Cover and cook on low for 7-8 hours or high for 3 ½-4 hours, until the vegetables and meat are tender and cooked through.
Remove and discard the bay leaf. Taste and season with salt and pepper as needed. Serve.