Ropa vieja, the classic Cuban dish of shredded stewed beef flavored with a vinegary tomato and pepper sauce, is a natural choice for the slow cooker, stewed all day and served with rice and beans.
Slow cookers are great at getting meat tender over a long period of time, but they can also dull flavors, which means you've got to start big and bold. The first step is browning the beef (I use flank steak for its nice, long shreds) in a hot pan before it ever meets the slow cooker. For the sauce, I use a mix of beef broth and crushed tomatoes (enhanced with some tomato paste for a richer texture), along with onions, red pepper, garlic, and ground cumin.
Toward the end of cooking you add what really makes the dish: Spanish olives and olive brine. I've tried adding them at the beginning of cooking, and it doesn't work as well. Adding them at the end keeps the flavor brighter and fresher, without the salty effects you can get from overly concentrating during a slow cook. When the meat is tender, I shred it up using two forks.
For the beans, if you want to soak your beans overnight you can, though it's really not necessary here. By simply rinsing them you get a nice, soupy, "cowboy"-style pot that's perfect spooned atop rice, especially when its seasoned with some bacon and bay leaf. I've found that black beans take a bit longer to cook than pinto beans do, so allow at least 2 1/2 hours of cooking time on the stovetop.
Serve the dish with limes, cilantro and a bottle of Caribbean-style hot sauce.