1.Heat oil in a large deep saucepan; cook lamb, in batches, until browned all over.
2.Heat butter in same pan; cook onion and garlic, stirring, until onion softens. Add cumin and capsicum; cook, stirring, until fragrant.
3.Return lamb to pan with barley, rind, juice, stock and the water; bring to the boil. Reduce heat; simmer, covered, for 45 minutes. Uncover; simmer for 30 minutes or until lamb is tender.
4.Strain mixture over a large bowl; cover lamb mixture to keep warm. Return cooking liquid to pan; bring to the boil. Boil, uncovered, stirring occasionally, for 15 minutes or until sauce thickens slightly.
5.Divide lamb mixture among plates; top with sauce then with mint.
To freeze; complete the recipe to the end of step 3. Pack into freezer-proof containers, leaving a 2.5cm (1 inch) space to allow for expansion. Seal, label and freeze for up to 3 months. Thaw overnight in the fridge. Reheat in a large saucepan, then continue from step 4.