Place all ingredients for dressing in a food processor and process into a smooth sauce. If it's too thick, you can add a bit more water. Have a taste and add more salt or sugar to your taste. It should be savory and sweet
Preparing the salad:
Pick the leaves off the stems of water spinach. You may include some of the skinny stalks in too if you want and discard big tough stalks. Bring a large pot of water to a boil. Blanch the water spinach until soft and then refresh with water. Do the same with the bean sprouts and green beans. Green beans may take about 3-4 minutes. Boil the potato and pumpkin (if using) for about 1-2 minutes
Arrange the vegetable on a large salad bowl or platter. Pour the dressing over and reserve some on the side. Mix it to make sure the peanut sauce coats the veggies. Serve