Cucumber Avocado Rolls with Tuna Ceviche

Lately, I've been trying to put more focus on plate presentation.  You do eat with your eyes first so it's an aspect of culinary arts I feel that I've put on the back burner for too long.   Yes, ultimately it's more important that what I make tastes good, but it I can elevate my food to appeal to multiple senses, I'm up for the challenge.  

For one of my first attempts, I took something that I know I can make well - ahi tuna ceviche, and thought about ways I can make a pile of pinkish grey chopped fish more aesthetically appealing.  The best answer I could come up with was to hide it.  Start by taking a sushi rolling mat (you can get one a Home Goods or Bed, Bath & Beyond for about $5) and wrap it in cellophane. Next take a ripe (but not too ripe) avocado, slice it in half and gently scoop out the flesh, trying to keep the halves as intact as possible.  With a Y-shaped peeler, very carefully shave off layers from the outer side of the avocado and arrange them on the mat, slightly overlapping the edges.  Next take an English cucumber, slice it in half and peel.  Once again, with your Y-shaped peeler, shave off thin layers from the cucumber and form a layer onto of the avocado.  

To make your ceviche, dice a block of fresh ahi tuna into 1cm square cubes.  The higher quality the fish, the better your final product will be.  Since ceviche is essentially a raw preparation, you won't be able to mask imperfections in the fish.  If you live in the Greater Boston area, H Mart is Burlington has the best tuna I've ever had the pleasure of cooking with.  

In a separate dish, combine the juice of 1/2 of a tangerine and one lemon with 1/4 cup high quality olive oil, three tablespoons cider vinegar, one tablespoon freshly grated ginger, one tablespoon finely chopped cilantro, kosher salt and white pepper. Pour over your tuna, gently mix to combine and allow to rest for about 10 minutes.  

Using a mesh sieve, drain the ceviche to remove any excess liquid.  Spoon a small amount onto the front side of your cucumber slices.  Using the mat, gently roll the ingredients together, pressing lightly to seal.  Use a wide spatula to transfer to your plate and score the roll to ease in cutting.  Sprinkle the top with white and black sesame seeds.  Much prettier than a pile of fish on top of a cucumber salad.