1. Cut cucumber slices into half-moon shapes. Place cucumbers in a large bowl with sea salt. Toss well. Let marinate at room temperature for 30 minutes. Rinse well to remove salt.

2. Slice eggs in half. Separate yolks and whites. Chop whites and set aside. Mash egg yolks with mustard, yogurt, honey, and vinegar.

3. Toss together cucumbers, egg whites, and egg-yolk mixture. Wash spinach and remove stems. Arrange on 4 salad plates. Spoon cucumber salad on top. Garnish with dill sprigs. Serve at room temperature.