Dice the cucumbers into small, even pieces, sprinkle with salt, and let sit in a colander for 15 minutes to draw out moisture.

In a mixing bowl, combine yogurt, crumbled feta, chopped herbs, lemon zest, lemon juice, and pepper, and mix until smooth.

Fold the drained cucumbers into the yogurt mixture until evenly coated.

Spread the cucumber filling on one slice of toasted bread, layer sprouts, add onion slices if using, then top with another slice of bread. Cut in half to serve.

Serve immediately to enjoy fresh flavors, optionally paired with potato chips or fresh fruit.