Put the cucumbers in a colander over a bowl or in the sink and toss with 1-1/2 teaspoon of the salt. Let them sit for 30 minutes to draw out the juices and remove any trace of bitterness. Meanwhile, core and seed the pepper and cut three-quarters of it into 1-inch pieces. Wrap the remaining quarter and refrigerate; you'll need it later. Cut the avocado in half, peel one half, and cut it into 1-inch chunks. Lightly coat the cut surface of the remaining half with oil, wrap it in plastic, and refrigerate for later.

Rinse and drain the cucumber. Put the cucumber, pepper, avocado, onion, the remaining 1-1/2 teaspoons salt, and the pepper in a food processor and puree. Transfer the puree to a large bowl and reassemble the processor. Process the bread, garlic, and herbs until the bread is reduced to crumbs and the herbs are fully chopped. Add the oil and vinegar to the mixture and process briefly to thoroughly combine. Add the bread mixture and 1 cup water to the cucumber puree and stir until well blended. Cover and refrigerate at least 2 hours or overnight. Let come to a cool room temperature before serving.

When ready to serve, peel the reserved avocado half and cut it into 1/2-inch dice. Cut the reserved pepper into 1/4-inch dice. Stir the soup and assess its consistency. If it seems too thick, add water until it's thinned to your liking. Season to taste with salt and pepper. Divide the soup among shallow bowls and garnish with the avocado and pepper. Drizzle about 1 teaspoon of olive oil over each bowl and serve.