Cut the cucumber and carrot into thin strips.
Slice the onion thinly.
Drain the oil from the tuna using a strainer.
Make the sauce by mixing gochujang, soy sauce, vinegar, sugar, and minced garlic.
Boil the noodles, rinse them in cold water, and drain completely.
Add the sauce, vegetables, and tuna to the noodles and mix well.
Serve in a bowl and top with halved boiled eggs.