In a large pot, add the ginger and lemongrass, stock, and bring to a boil. Turn heat to medium and let simmer for 30 minutes, to allow the lemongrass to release its flavors.

Then add in the coconut milk, lime juice, Siracha sauce, fish sauce, and sugar. Stir well, and let cook for about 10 minutes.

In the meantime, blanch the broccoli, zucchini, and carrots in a pot of boiling water for about 2 minutes, just to soften them a bit.

Divide all the vegetables equally into 6 bowls (both the raw vegetables and the blanched vegetables). Now evenly distribute the soup into each bowl by ladling it over the vegetables.

Top with cilantro and serve immediately.