Prepping the Cucumber:
Cut and discard the ends. Then as a way to create a more decorative cup, but also make it easier to eat, peel off three stripes, spaced evening down the sides of the cucumber. Then cut crosswise into 3/4 cup thick slices. When scooping out the cups of each slice, use a small melon baller or a metal teaspoon. Be sure not to go all the way through. Discard the scooped portion.
Marinate the cups:
Whisk together the rice vinegar and the honey in a small bowl until the honey dissolves. Add the cucumber cups; cover tightly with plastic wrap and refrigerate for 30 minutes.
Prepare the filling:
Mix together the remaining ingredients in a medium size bowl: sour cream, mayonnaise, red onion, feta cheese, dill (keep a pinch extra for garnish) and salt.
Assemble the cups:
Remove the cucumber cups from the marinade and place on a paper towel to absorb any extra liquid. Then fill each cup with the filling (approximately 1 teaspoon). Arrange on a serving plate, cover and refrigerate until ready to serve. Add a slight dash of chopped dill to garnish each bite.