Heat the oil in a small pan. Add the leeks and saute until softened, about 3 - 5 minutes.
Transfer the leeks to a blender, followed by the cucumber, zucchini, cilantro, scallions and spices. Add 1/2 cup coconut milk and 1 cup of water. Blend on high until smooth.
Remove the lid and add the avocado and remaining liquid, blending again until smooth. For a thinner soup, add additional liquid 1/4 cup at a time (blending between each addition), until you've reached your desired consistency.
Taste and adjust seasonings as desired.
If soup is at your desired temperature, serve immediately. If not, chill in the fridge until cold.
To serve, pour the soup into bowls and optionally garnish with chopped zucchini, a drizzle of olive oil and some fresh cracked pepper.