Marrow soup - Good Food Middle East

Ingredients

• 1 tbsp vegetable oil
• 2 onions, roughly chopped
• 250g potatoes, roughly chopped
• 1 marrow (about 750g), peeled, deseeded and roughly chopped (see tip, below)
• 1-2 tbsp curry powder, to taste
• 500ml vegetable or chicken stock
• 400g can butter beans, drained
• 400ml can light coconut milk
• small handful of coriander leaves