Soak whole mung in water for a couple of days, changing water frequently to ensure it softens the grains without any effect on it's freshness. Changing water frequently helps to remove the unpleasant "gas" effect of eating mung beans. From Ayurvedic standpoint, it helps to remove the Vata dosha from bean-grains. Also fresh sprouted mung beans will work very well for this soup.
Once the mung beans are ready, heat some oil in the pan and add mustard seeds. As they pop- you could add some asafoetida (if you have available). Asafoetida is the mother of spices to counteract Bean-gas-effect! Plus the fact that it helps calm Vata dosha and is perfect spice for coming colder days, just makes it all the more important nutritious ingredient for this soup. From a taste standpoint, if you don't have it- don't sweat it! You can still carry on...
Once mustard seeds have popped add the soaked and cleaned mung beans and one can of coconut milk. Flavor with Thai curry spice, pinch of turmeric, red chili powder and salt to taste. Finally some freshly ground black pepper and handful of finely chopped green spring onions completes the ingredient list. Cook to a boil, lower heat and simmer for another few minutes. Close the lid and let stand for a few more minutes and your super tasty soup is ready to serve! Garnish with herb and garlic whole wheat croutons or unsalted crackers for a yummy meal.