Spiced Lamb Roast

Name: Spiced Lamb Roast
Prep time: 20 min
Cook time: 29 h 50 min
Total time: 29 h 50 min
Yield: 12 portions
Ingredients: 1 Tbsp olive oil; 3 tsp black mustard seeds; 250 g onion; 2 tsp fresh root ginger; 4 garlic cloves; 2 tsp coriander seeds; 2 tsp cumin seeds; 2 dried bay leaves; ¼ tsp ground turmeric; 120 g tomato purée; 2 fresh red chillies; 1 tsp fine sea salt; 100 g Greek yoghurt; 200 g coconut milk; 2500 g lamb shoulder; water