In a bowl, combine vinegar, sugar, salt and 2 to 3 tablespoons hot water. Stir to dissolve sugar. Place cucumber slices in bowl with marinade and toss. Let sit, refrigerated for 1 hour. Plate tatsoi greens, tossed with Ginger Lime Dressing. Put cucumber on greens and garnish with avocado and lime wedges.
In a small bowl, mix together the wasabi and water to form a paste then transfer to a blender and all lime, juice, sugar, Dijon and ginger. Start the blender and slowly add olive oil. Season with salt and pepper to taste.