- Feel free to substitute herbs for the edible flowers. You’ll want to use more delicately flavored herbs so they don’t overwhelm the soup. Fennel fronds, tarragon, thyme leaves, small mint or basil leaves, or a few snipped chives would work well.
- If you don’t plan to eat all the soup at once, add the lemon juice and vinegar only to what you plan to eat at one sitting. They will cause the soup to lose its color if added too far in advance. (It tastes fine, but looks a little drab.)
- For a vegetarian or vegan version, substitute a creamy feta or some finely-chopped pistachios for the prosciutto.
Heat 4 tablespoons of the oil in a Dutch oven or heavy-bottomed stock pot over low heat. Add the fennel and half the salt. Cover and cook, stirring occasionally, until very tender, about 20 minutes. You don’t want the fennel to brown. Add the zucchini and cook for 5 minutes. Add the spinach, parsley, peas, garlic, the remaining ½ teaspoon salt and 3 cups of water. Raise the heat to medium and cook, covered, until the spinach has just wilted and the peas are tender, about 5 minutes longer. Take care not to overcook the vegetable or the soup will lose its bright color.
Remove the soup from the heat and puree in a blender in batches until very smooth. Take care not to fill your blender more than ⅔ full so the steam from the soup doesn’t blow the top off and burn you. If you don’t have a blender powerful enough to puree the soup very fine, strain it through a fine mesh sieve. Transfer the pureed soup to a large bowl, thin with cold water to your desired consistency and place in the fridge to cool completely.
Remove the soup from the fridge 30 minutes to one hour before serving so it can warm up a bit. (When it’s ice cold, it looses some of it's depth.) Add the lemon juice and vinegar just before serving. Taste and add more salt and/or acid as necessary.
While the soup is warming up, crisp the prosciutto. Heat the remaining tablespoon of oil over medium heat in a large sauté pan. Add the ham and cook, turning once or twice until crisp, about 5 mins. Transfer to a paper towel lined plate to cool slightly.
To serve, ladle the soup into serving bowls and garnish with a swirl of the pistachio (or olive) oil. Top with edible flowers and serve with the crispy prosciutto.