Begin by dicing your English cucumbers into small pieces, then sprinkle them with salt in a colander. Let them sit for at least 15 minutes to draw out moisture.

In a large mixing bowl, combine plain Greek yogurt, crumbled feta cheese, and your choice of fresh herbs. Add lemon zest, juice, and black pepper. Blend until smooth.

Fold the prepared cucumbers into the yogurt-feta mixture until evenly coated.

Toast the bread slices until golden. On two slices, layer sprouts, the cucumber mixture, and then onion slices. Top with another slice of bread and cut in half.

Serve the sandwiches immediately to maintain crispness.