Dice two English cucumbers into small cubes and place them in a colander. Sprinkle salt over the cucumbers and allow them to sit for 15 minutes.

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

Pat the drained cucumbers dry with a paper towel.

Fold the dried cucumbers into the yogurt-feta mixture until well-coated.

Toast bread slices until golden brown, about 3-4 minutes. Let cool slightly.

Spread the cucumber and yogurt-feta mixture on a slice of toasted bread, adding sprouts on top. Place another slice of bread on top.

Evenly distribute onion slices on top of the cucumbers in the assembled sandwiches.

Cut each sandwich in half and serve immediately.