Heat a large Dutch oven over medium-high heat. Coat pan with cooking spray. Add onion; sauté 10 minutes or until tender and golden brown. Add garlic; sauté 1 minute. Spoon onion mixture into a large bowl.
Place flour in a shallow bowl or pie plate. Dredge lamb in flour, shaking off excess. Heat oil in pan over medium-high heat. Add half of lamb mixture; sprinkle with 1/4 teaspoon salt. Cook 6 minutes, browning on all sides. Add browned lamb to onion mixture. Repeat procedure with remaining lamb mixture and 1/4 teaspoon salt.
Add pomegranate molasses and broth to pan, scraping pan to loosen browned bits; bring to a boil. Stir in lamb mixture. Cover, reduce heat, and simmer 1 hour or until lamb is just tender.
Stir in carrot and chickpeas. Simmer, uncovered, 45 minutes or until lamb is very tender. Remove from heat; stir in remaining 1/2 teaspoon salt, mint, and pepper. Serve over couscous.