Stir 2 ounces cream cheese, 1 tablespoon yogurt, 1 tablespoon chives, 1 tablespoon dill, ¼ teaspoon pepper and a pinch of salt together in a small bowl until well blended.
Spread the mixture evenly on one side of each bread slice.
Top 1 slice with avocado slices, ⅓ cup cucumber, ¼ cup spinach and 1 tablespoon onion.
Drizzle with 1 teaspoon lemon juice, then top with the remaining bread slice, cream cheese–side down.
Cut in half diagonally.
