Place sliced cucumbers in a resealable bag. In a bowl combine rice vinegar, sugar, salt, and sriracha seasoning. Whisk well to combine. Pour pickling liquid into bag with cucumbers. Let sit, refrigerated, for 4 hours or overnight.
Strain cucumbers, reserving pickling liquid.
In a bowl combine wakame, cucumbers, soy sauce, and 2 tablespoons of reserved pickling liquid. Toss to mix.
Plate salad in bowls; top with sesame seeds, sesame oil, and extra sriracha seasoning as desired.