In a food processor, grind the coconut, green chillies, ginger and garlic to a pulp.
In a large pot or frying pan, heat the oil over medium high heat. Add the coconut/chilli paste and cook for 1 to 2 minutes. Add the vegetables and saute lightly. Add the turmeric and ground coriander, and salt to taste. Once the veggies have softened slightly, about 5 minutes, add water to cover and increase heat to high; bring to the boil. Reduce to a simmer, and cook until the water has reduced and the vegetables are tender.
Just before serving, sprinkle with the fresh coriander and garam masala.