In a large bowl, combine chicken, cumin, onion, salt, pepper, and parsley. Using your hands, mix until well combined. Form mixture into 8 oval patties and put on a plate.
In a medium bowl, toss together cucumber, yogurt, and lemon juice. Season with salt and pepper.
In a large skillet, heat oil over medium-high. Cook patties until browned on all sides and cooked through, about 12 minutes total.
Meanwhile, heat chicken broth in a pot with cumin and red pepper flakes. When it comes to a boil, add the red bell peppers and couscous. Place a lid on top and turn off the heat. Let the couscous sit for 5-7 minutes, or until cooked. Fluff with a fork, add chopped parsley, and season with salt and pepper. To serve, scoop couscous onto plates, top with two koftas each, dollop with some cucumber yogurt sauce, and lemon wedges for squeezing. Top with fresh parsley or mint leaves.