Rinse barley in a sieve under cold running water; drain well.
Heat half the oil in a 4.5-litre (18-cup) slow cooker on sear (HIGH) setting; cook lamb, in batches, turning, for 15 minutes, or until well browned. Remove from cooker.
Heat remaining oil in cooker on sauté (MEDIUM) setting; cook onion, celery, carrot and capsicum, stirring, for 5 minutes or until vegetables soften. Add garlic, fennel seeds, paprika and bay leaves; cook, stirring, for 2 minutes or until fragrant. Add paste; cook, stirring, for 2 minutes. Stir in tomatoes, stock and barley. Return lamb to cooker; bring to the boil.
Cook, covered, on low, for 8 hours. Discard bay leaves; season to taste.
Serve lamb mixture topped with parsley and parmesan.
Accompany with a bitter leaf salad.Not suitable to freeze.