Prepare the broccoli by separating the florets and peeling the stems. Cut both into bite-sized pieces.

Rinse the broccoli under running water, then soak in water mixed with 1 tbsp vinegar for 10 minutes.

Boil water with 0.5 tbsp coarse salt, blanch the broccoli for 1 minute, and let it cool without rinsing.

Open the canned tuna and let it sit briefly to release any unwanted odors.

Mix ground sesame, soy sauce, oligosaccharide, mayonnaise, plum syrup, and pepper in a bowl to create the sesame mayo sauce.

Add the broccoli to the sauce, mix well, and adjust seasoning with salt as needed.

Add the drained tuna to the mixture and gently toss to combine.