Marrow curry

Name: Marrow curry
Prep time: 10 min
Cook time: 30 min
Total time: 40 min
Cuisine: Asian
Ingredients: 1 marrow peeled and cut into large chunks; 2 tbsp sunflower oil; 2 tsp black mustard seeds; 1 tsp cumin seed; 1 large onion finely sliced; 2 garlic cloves crushed; ½ tsp turmeric; ½ tsp chilli powder; 1 tsp ground coriander; juice ½ lemon; small pack coriander roughly chopped