1. In the bowl of a blender or food processor, combine cucumber, buttermilk, garlic, anchovy, scallions, jalapeño, fresh herbs, sherry vinegar and salt. Blend until smooth and adjust seasoning as needed.
2. Smash avocado slices on the toasted bread. Sprinkle with crumbled feta, squeeze the juice of the lemon half over the top and finish each with a drizzle of olive oil and some pepper. Transfer to a plate and set aside.
3. Distribute soup between 4 bowls and garnish with raw corn kernels, toasted pine nuts and/or red onion ~ and a drizzle of olive oil. Serve avocado toast on the side.