Wash the English cucumbers, then dice them into small, bite-sized pieces. Place in a colander and sprinkle with salt, allowing to drain for about 15 minutes.

In a bowl, combine yogurt, crumbled feta cheese, chopped fresh herbs, lemon zest, lemon juice, and black pepper. Blend until smooth and creamy.

Add the drained cucumbers to the yogurt mixture and fold gently until evenly coated.

Assemble the sandwiches by layering the filling on one slice of toasted bread, adding sprouts and onion slices, then topping with another slice.

Cut the sandwiches in half diagonally and serve immediately for the best taste and texture.