In a large pot or sauté pan over medium-low heat, add 1/4 cup of the vegetable broth, the ginger, garlic, and onion. Sauté for 3–5 minutes. Add the curry powder, mushrooms, and lemongrass, and cook until the mushrooms are tender.
Add the remaining vegetable broth, broccoli, lime juice, and coconut milk. Bring to a boil, then reduce the heat and simmer for 10 minutes.
During the last minute of cooking, stir in the zucchini noodles. Remove from the heat.
Divide among bowls and garnish with cilantro and red chili flakes, if using. Serve and enjoy!