Heat the oil in a large pan and fry the onion over a medium heat for 5 minutes until softened. Stir in the masala paste and cook for 1 minute. Turn down the heat and pour in the coconut milk, stirring.
Slowly pour in the stock. Add the butternut squash and bring to the boil. Then lower the heat, cover and simmer for about 10 minutes.
Add the beans and chopped pepper to the pan and cook, covered, for another 5-10 minutes until the squash is tender. Garnish with coriander and serve with rice and naan bread or chapatti.