If using pre-cooked shrimp, skip straight to step 3. Before making this cold appetizer recipe you will need to cook and chill the raw shrimp. Place a pan on medium heat and add half a Tbsp. of oil. When the oil is hot, place the shrimp in the pan. Season with salt and pepper and cook the shrimp for 1 minute on each side until bright pink.
Remove from the pan and leave to cool. When completely cool, chill in the fridge for at least 20 minutes.
Use a vegetable peeler to roughly peel the cucumbers. This doesn't have to be perfect; a few strips of green skin left behind can add a nice effect to the finished shrimp hors d'oeures.
Slice off and discard either end of the cucumbers then cut up into inch thick pieces. Each piece will become a cucumber canape cup.
Use a melon baller (or a measuring spoon) to hollow out the seeds from the center of each cucumber cup. You may also need to use a knife if you can't get deep enough with the melon baller or spoon. Be careful not to go all the way through to the other side.
In a small bowl, mix together the yogurt, lemon juice, granulated garlic, and finely chopped mint leaves to make homemade tzatziki filling. Season with salt pepper and mix in well. Taste and adjust as necessary.
Transfer the tzatziki filling to a piping bag. Line up the cucumber cups and carefully fill each cup with the tzatziki. Don't fill all the way to the top, but leave a small gap, as the level of the filling will rise when the shrimp and herbs are added.
Place a chilled shrimp over the lip of each cup with the head end in the filling and the tail end hanging outside of the cup.
Top with herbs, then serve!