Chop the produce: Wash the 1 English cucumber (long seedless), finely chopped thoroughly. Finely chop the cucumber (no need to peel — the skin is tender). Chop 1 tablespoons fresh dill, chopped and 1 tablespoons fresh flat-leaf parsley, chopped finely and set aside.
Mix the soup: Pour 32 ounces European-style plain yogurt (full-fat) into a large bowl. Add the chopped cucumber, 1 tablespoons fresh dill, chopped, 1 tablespoons fresh flat-leaf parsley, chopped, 2 garlic cloves, crushed, 1 tablespoons olive oil, and 1.5 teaspoons salt. Pour in 1 cups cold water and stir everything together until fully combined and smooth.
Taste and adjust: Taste the soup and adjust salt as needed. If you prefer a thinner consistency, add a splash more cold water and stir.
Serve and garnish: Pour into a serving bowl. Top with a drizzle of 1 tablespoons olive oil, for drizzling (garnish), a scatter of 1 tablespoons extra fresh dill and parsley (garnish), and a handful of 2 tablespoons chopped walnuts (optional garnish). Serve immediately and enjoy!