Place the couscous in a large bowl and pour 1½ cups hot tap water over the top. Cover and let stand for 5 minutes; fluff with a fork.
Form the beef into 12 small ½-inch-thick patties. Sprinkle with the cumin, oregano, 1 teaspoon salt, and ¼ teaspoon pepper.
Heat 1 tablespoon of the oil in a large skillet over medium heat. Add the patties and cook to the desired doneness, 4 minutes per side for medium.
Toss the couscous with the scallions, tomatoes, cucumber, lemon juice, remaining oil, 1¼ teaspoons salt, and ¼ teaspoon pepper.
Serve with the burgers and hummus, if using.