Trim the ends off the cucumbers. Cut into cubes.

Wash the watercress, remove any thick stems, then roughly chop. This should yield about 2 cups worth.

Place half the cucumbers and most of the lemon juice into your blender container. Puree. Add the remaining cucumbers, watercress, garlic, and jalapeno. Puree until smooth (you may need to work in batches, depending on the strength and size of your blender).

Cut the avocado in half, take out the pit, peel, then cut the avocado flesh into cubes. You should have just under 1 cup diced avocado. Add to the cucumber puree, along with 1 teaspoon of salt. Process again. The soup will be much thicker and creamier.

Stir everything together in a bowl, then taste. Add more lemon juice and salt if desired, a little bit at a time until the balance is right for you.

Chill the soup at least 30 minutes.

Serve in small bowls with yogurt or a drizzle of the olive oil, followed by tomato cubes and croutons.

This soup is best eaten within a couple days, as the creaminess from the avocado will start to disappear and the soup becomes progressively more peppery from the watercress. It can be frozen in individual servings and later defrosted or eaten as a yummy vegetable slushy. If the taste becomes too one-note, restore the soup by adding a few chunks of fresh avocado and give it a quick puree.