Cucumber salad: Toss cucumbers, onions, rice vinegar, sugar, and salt in a medium sized bowl. Let it marinate at room temperature for 1 hour.
Burger: Mix ground turkey, rice, panko, green onions, egg, sesame oil, soy sauce, Thai chile, and sugar very well. Make into 4 patties. Season with salt and pepper.
Heat peanut oil in a large skillet over medium-high heat. Saute burgers until cooked through, approximately 5 to 6 minutes per side (depending on how thick you make them).
Wasabi mayonnaise: While burgers are cooking, toast buns, and mix mayonnaise, with wasabi powder, ginger, and lemon peel in a small bowl.
Drain cucumber salad well.
Smear 1 tablespoon wasabi mayonnaise on toasted bun halves, spread with a layer of drained cucumber salad, then top with burger and cover with bun top.