In a small bowl, combine the beef, basil, oregano and salt. Shape into 1/2-in. balls. In a large skillet coated with cooking spray, brown meatballs; drain. Remove meatballs and set aside.
In the same skillet, brown onion in oil. Add greens and kale; cook 6-7 minutes longer or until wilted.
In a Dutch oven, combine the greens mixture, meatballs, stock, vinegar, pepper flakes and pepper. Bring to a boil. Reduce heat; cover and simmer for 10 minutes. Return to a boil. Stir in couscous. Reduce heat; cover and simmer, stirring once, until couscous is tender, 10-15 minutes.