Remove the cabbage leaves and wash them thoroughly.
Blanch the cabbage leaves in boiling water for 1-2 minutes, then rinse in cold water.
Drain the oil from the canned tuna using a strainer and place the tuna in a bowl.
Add chopped onion, carrot, salt, and pepper to the tuna and mix well.
Place a scoop of rice on a cabbage leaf, then add the tuna mixture on top.
Roll up the cabbage leaf and arrange on a plate.