Season beef with salt and pepper. Heat a large skillet over medium heat and add a tablespoon olive oil and half of beef, in a single layer; cook, turning a few times until browned on all sides. Working in batches and then transfer to a 5-to-6-quart slow cooker.
Add the sliced shallots and wine to the skillet and cook, scraping up browned bits, until the wine has evaporated. This takes only a couple of minutes. Transfer to slow-cooker.
Stir in the tomatoes with their juices, the fennel, rosemary, and orange zest. Cover and cook on high until meat is fork-tender, about 6-7 hours.