In heavy frying pan, heat 1 T oil over medium-high heat and brown half of beef cubes, turning several times so it's well browned on all sides. Put beef in crockpot and brown the rest of beef, adding more oil if needed. Put second batch of browned beef cubes in crockpot. Add beef broth to frying pan, scraping up any browned bits from the bottom of the pan, and simmer until beef broth is reduced to 3/4 cup. Add reduced broth to crockpot.
While beef is browning, sliver garlic and cut olives. Add garlic and olives to crockpot along with rinsed capers, bay leaves, oregano, canned tomatoes and juice, tomato sauce, red wine vinegar, and pepper.
Cook on high for 2 hours, then taste for seasoning and add tomato paste if desired. Cook another 1-2 hours, until meat is tender and flavors are well blended. (This could also be cooked on low for 6-8 hours.) Serve hot.