Cut apart the fronds, stalks, and bulb of the fennel. Set the fronds aside in two batches, with about ¼ cup for garnish (these should be the thinnest ones) and put the rest in the bowl of your blender.

Heat 2 Tablespoons of olive oil in a large skillet over medium-low heat. When hot, add the onion and fennel bulb and stalks, sprinkle with ¼ teaspoon of salt and gently saute, stirring frequently, until tender and translucent all the way through (see note), about 12-14 minutes.

Blend the Fennel and Onion with Broth

Add the sauteed fennel and onion and the vegetable stock/broth into the blender with the fennel fronds. Blend on high speed until smooth, 2-3 minutes with a Vitamix blender (see note). Taste the blended soup and stir in salt to taste if needed. Pour the soup into a large bowl or sealable container to cool.

Heat the remaining 1 Tablespoon of olive oil in the same skillet over low heat. When hot, add the cucumber cubes and sprinkle with ⅛ teaspoon of salt. Saute, stirring often, until barely translucent on most sides, 2-3 minutes.

Transfer the cucumber cubes into the container with the soup.

Cover the soup and if it’s hot, allow it to cool before putting it in the refrigerator. Chill until cold, at least 1 hour.

Distribute the soup and cucumber cubes into serving bowls. Garnish generously with chopped dill, fennel fronds, lemon zest, and a drizzle of olive oil.