Preheat the oven to 200 degrees Celsius/ 400 degrees Fahrenheit. Grease the baking dish with a little bit of vegan (or regular) butter.
Prepare vegetables: Peel the potatoes and cut them into cubes. Next, cut the pumpkin into similar sized cubes (if using Hokkaido pumpkin there will be no need to peel it). Place the vegetables into the prepared dish, add salt and pepper to taste and mix with your hands.
Prepare the rest of the ingredients: Top and tail the lemon grass sticks and remove their outer leaves. Chop them very very finely. Next, peel and grate the ginger. Remove the seeds of the chili (or leave them there if you like things hot) and chop the chili very finely. Place all these ingredients in a bowl and stir in the coconut milk.
Bake: Pour this mixture over the potatoes and pumpkin, dot with the remaining butter or vegan alternative, and bake for 40 or 50 minutes until the potatoes and the pumpkin are very tender. Sprinkle with parsley.
Serve with salad or as a side dish.
Notes
Use a flavorful sort of pumpkin, like Hokkaido/red Kuri squash or butternut squash. Hokkaido doesn't need to be peeled.