Combine the cucumber, avocado flesh, jalapeno, lemon juice, cilantro, salt, and ½ cup water in a blender. Blend until smooth, adding more water as needed. Taste, and adjust seasonings as desired.
Chill the soup for at least an hour (preferably 2 or more) in the fridge before serving. Serve with chopped pineapple and cucumber.
Notes
For more of a lemon flavor, add some lemon zest in addition to the juice.
If you want the soup to be spicier, use a second jalapeno.
For a variation, use fresh dill instead of cilantro.
Other topping ideas include: fresh mango, feta cheese, or croutons.
Leftovers will last in an airtight container in the fridge for 3 to 5 days.