Shred the imitation crab meat into thin strips using your hands or a knife.
Julienne the cucumber and carrot into thin matchstick pieces.
In a bowl, mix mayonnaise, sugar, sriracha (if using), and rice vinegar to make the dressing.
Add the shredded crab, cucumber, and carrot to the dressing and toss until well coated.
Sprinkle panko breadcrumbs on top for extra crunch.
Chill in the refrigerator for 10 minutes for the flavors to meld (optional but recommended).
Serve fresh and enjoy as a side dish or light meal.