In a medium bowl, combine cream cheese, mayonnaise, and seasoning mix. Cover and refrigerate at least 30 minutes to blend flavors.
To assemble, top each square of bread with cream cheese mixture and a cucumber slice.
Ranch dressing mix: You can certainly buy a packet at the supermarket. Or, to make Homemade Ranch Dressing Mix, in a small bowl, whisk together 2 tablespoons powdered buttermilk, 2 ½ teaspoons dried parsley, 1 teaspoon dried minced onion, 1 teaspoon garlic powder, 1 teaspoon onion powder, ½ teaspoon dill weed, and ¼ teaspoon salt.
High-quality sandwich bread: You want something sturdy that can stand up to a schmear of cream cheese. A store-bought or homemade croissant, sliced in half, would also make an ideal vessel if you’re serving Cucumber Sandwiches as part of a brunch menu.
Hot house cucumbers: Also labeled as “English cucumbers,” these have thinner skins, sweeter flesh, and less seeds than traditional cucumbers. If you can’t find the hot house variety, substitute for 2 to 3 regular cucumbers, peeled and thinly sliced.
Yield: This recipe makes enough appetizer-sized servings, five mini sandwiches each, to feed 16 people. Double or halve the recipe as appropriate for your crowd.
Storage: Store leftovers covered in the refrigerator for 1 day.