vegetable oil • boneless meat, cut into 1 1/2-inch pieces • large onions, cut into 6 wedges each • can whole tomatoes, cut into large chunks • beef broth • minced garlic • each cumin and oregano • fresh ear corn cobs, cut crosswise in 1 1/2-inch pieces • medium zuchhini, quartered and cut into 1 1/2-inch pieces