Dice the English cucumber into small, even pieces. Sprinkle a pinch of salt over the cucumber and let it rest in a colander for 10 minutes.

In a large mixing bowl, combine low-fat Greek yogurt, crumbled feta cheese, chopped herbs, lemon juice, lemon zest, and black pepper. Mix thoroughly until creamy.

After 10 minutes, drain and pat the cucumber dry with paper towels.

Add the drained cucumber into the yogurt mixture and fold gently until well coated.

Lay slices of bread on a clean surface. On one slice, add alfalfa sprouts, followed by the cucumber filling, and top with red onion. Place another slice of bread on top and gently press down.

Slice the sandwiches in half and serve immediately with cherry tomatoes or fresh fruit.