Heat coconut oil in a large pot over medium heat and sauté onion until softened, about 5 minutes.
Add garlic, curry powder, and cumin, stirring constantly for 1 minute until fragrant.
Add chopped zucchini and vegetable broth, bring to a boil, then reduce heat and simmer for 15-20 minutes until zucchini is very tender.
Use an immersion blender to puree soup until completely smooth, or carefully transfer to a blender in batches.
Stir in coconut milk and heat through for 2-3 minutes, then season with salt and pepper.
Serve hot, garnished with fresh cilantro if desired.