To make the soup: Cut the ends of the leeks. Cut them lengthwise in half and then into thin half moons. Place the cut leeks in acolander and wash under running water to remove as much dirt as possible.
Pour the oil into a large pot over medium-high heat. Once hot, but not smoking, add the leeks and cook for 8-10 minutes, or until they’re soft.
In the meantime, trim the ends of the asparagus. Chop the asparagus stalks into 2-3 cm pieces and add them to the pot with the leeks. Add the salt, stock and coconut milk, bring to a boil and, once boiling, decrease the heat to medium and cook for 5-6 minutes or until the vegetables are soft.
Add the lime zest and juice and, using a blender, puree the soup until smooth (you might have to do this in batches). Have a taste and adjust the seasoning, adding freshly ground black pepper and more salt if needed.
To make the crispy beans: Dry the beans with a clean towel to remove as much moisture as possible. In a mortar an pestle, combine the dried chillis with the salt and crush until you get a fine powder. Add the oil, beans and chilli seasoning to a large skillet over medium heat. Mix with a wooden spoon to coat the beans evenly, and cook for 15 minutes or until they’re crisp and golden brown.
Serve the soup in bowls with a few tablespoons of the crispy beans on top. Add a little extra lime juice and zest to the soup right before digging in, if desired.