To make the marinade, combine the soy sauce, sesame oil, rice vinegar, garlic, ginger, scallions and red pepper flakes in a bowl. Reserve 1/4 cup for finishing the sauce when plating.
In a sealed container or ziplock bag, combine the chicken and remaining marinade. Marinate for 30 minutes on the counter or overnight in the fridge.
When ready to cook:
Heat your Spark to 500°F and brush your grill grates with oil. Place the chicken on the grill and cook for about 20 minutes, flipping each piece over after 10 minutes. If using your Spark temperature probes, you are looking for an internal temperature of 165°F.
Meanwhile, cook your rice per the package instructions.
Slice the cucumbers into spears, wash the herbs well and pinch off the leaves from the stems.
Plate the chicken with a scoop of rice and garnish with the cucumber spears, fresh herbs and a drizzle of the reserved marinade.