Wash the cucumber thoroughly and slice it thinly into half-moon shapes.
Finely chop the onion and carrot as well.
Drain the oil from the canned tuna using a strainer.
In a bowl, add rice, cucumber, onion, carrot, and tuna, then add the bibimbap sauce (gochujang, soy sauce, sesame oil, sugar).
Mix everything well so the ingredients are evenly combined, then serve.
Sprinkle roasted sesame seeds on top to finish.