Orange and chickpea couscous salad

• 1 ½ cups vegetable stock
• 1 ½ cups instant couscous
• 1 cup cooked chickpeas
• ¼ cup currants
• 2 medium oranges, peeled and segmented
• ½ cup spring onions, chopped

Dressing

• ½ cup low-fat plain yoghurt
• ⅓ cup lemon juice
• 2 cloves garlic, crushed
• 1 tsp ground cumin