Start by making a corn broth: Cut kernels from 4 ears of fresh corn. You should have about 3 cups, maybe a little more. Set aside one third for the garnish, and reserve the other two thirds for the soup. Put the corn for the soup in a bowl and, working over it, scrape the cobs with the back of your knife to extract the sweet corn "milk." Set the bowl aside. Break the scraped cobs up into pieces that will fit comfortably in a saucepan and pour the vegetable broth over. Pluck enough leaves and soft stems from the cilantro to make about 1/2 cup finely chopped. Set aside 2 tbsp for the garnish, and the rest for the soup. Take a handful of the cilantro stems and toss them in with the corn cobs and vegetable broth. Simmer slowly, covered, on a back burner over low heat while you do the rest of your prep.
Next, make the crab, corn, and pepper garnish: In a medium skillet (a 10-incher is good) over medium heat, warm 1 tbsp coconut or olive oil (or butter). Add the 1/3 of the corn kernels you reserved for the garnish, along with the green onions, the bell pepper, half the minced jalapeno, and your reserved 1/2 cup of finely diced zucchini. Saute 5 minutes or until lightly browned and the corn is tender, but not mushy. Remove from heat and season with salt. Let cool slightly, then gently fold in crab meat and cilantro. Adjust for seasoning and set aside until ready to serve.
Now make the soup: Melt butter or coconut oil in a large soup pot or Dutch oven over medium heat. Add onions and saute until tender and translucent and beginning to brown, 5-10 minutes. Add potatoes and cook for a minute or so. Add the remaining corn kernels (and accumulated corn milk), the remaining jalapeno, zucchini, ginger, curry powder, and a good pinch of salt. Stir well and cook for another minute or so, then strain your corn-and-cilantro-infused vegetable broth into the pot. Bring to a boil. Reduce heat, cover, and simmer until potatoes are tender, 15 minutes or so. Stir in coconut milk, the juice of half a lime, the mint, and the remaining cilantro (retain a few pinches for additional garnish). Remove the pot from heat and let cool.
Puree in batches in a blender or food processor, or directly in the pan using an immersion blender. Put pureed soup through a fine-mesh sieve to remove any stray solids (such as corn or zucchini skins) and ensure a velvety-smooth consistency. Add a little water or additional broth if soup is too thick. Adjust for lime juice and salt. Cool to room temperature, then chill in refrigerator several hours before serving, but preferably overnight, as this is definitely better the next day. (Taste again for salt once the soup is properly chilled--cold soups often need more salt than warm ones.) When ready to serve, ladle soup into shallow bowls and garnish each with a heaping spoonful of the crab, corn, and pepper mixture. Scatter additional cilantro and mint over and serve.