Lamb Meatballs With Yummy Yoghurt Dressing

• 500 g lamb mince
• 1 large brown onion, finely diced
• 2 tsp cumin, ground
• 1 cup wholemeal couscous
• 1 Lebanese cucumber, diced
• 60 g rocket
• 250 g cherry tomatoes, halved
• 1 cup Greek yoghurt
• 3 cloves garlic, crushed
• 2 tbsp lemon juice