How to Make It
In a large saucepot over high heat, combine the coconut milk, vegetable stock, fish sauce, sugar, lemongrass, ginger, garlic, sliced shallot, Sriracha, lime zest and salt. Bring mixture up to a boil, then reduce to a low heat and simmer for 30 minutes.
Transfer soup into a large bowl and cover with plastic wrap for 30 minutes. Strain soup through a fine mesh sieve into the saucepot and place over high heat.
To serve, add the chopped kale in handfuls, letting the leaves wilt into the soup, about 4 minutes. Squeeze in the lime juice, adjust seasoning with salt and additional chili sauce, and garnish with chopped cilantro.