Steps

1. Thinly slice 1/8 onion and then finely mince it.
   🕒 00:02
2. Add 1/2 tsp Mentsuyu (Noodle Soup Base) and 1/3 tsp Honey to the minced onion, mix well, and let it marinate for 5-10 minutes.
   🕒 00:10
3. Cut off the core from 80g cabbage and slice it into slightly thick shreds.
   🕒 00:19
4. Place the shredded cabbage in a microwave-safe bowl, cover loosely with plastic wrap, and microwave on 600W for 30 seconds. After heating, cover and let it cool down.
   🕒 00:27
5. Thoroughly drain the oil from 1 can tuna.
   🕒 00:38
6. Combine the marinated onion with the drained tuna, add 1 tbsp Mayonnaise, and mix well.
   🕒 00:44
7. Thoroughly pat dry the moisture from the cooled cabbage.
   🕒 00:50
8. Spread 5g salted butter on one side (the inner side) of 2 slices of bread.
   🕒 00:56
9. On the buttered side, place 1 slice of melting sliced cheese, then spread the prepared tuna-mayo mixture over it.
   🕒 01:02
10. Place the dried cabbage on top of the tuna-mayo, and then another slice of melting sliced cheese.
    🕒 01:08
11. Cover with the other slice of bread and gently press down with your hands.
    🕒 01:10
12. Add 5g salted butter to a frying pan, melt it over medium heat, and spread it evenly across the pan.
    🕒 01:16
13. Place the sandwich in the buttered pan, and cook over low heat for 2-3 minutes, pressing down, until golden brown.
    🕒 01:22
14. Once one side is golden brown, flip it over, add the remaining 5g salted butter, melt it, and press down to coat the bread while cooking.
    🕒 01:34
15. Remove from the pan once both sides are golden brown.
    🕒 01:47
16. Cut the cooked sandwich in half.
    🕒 01:50