• Gather all the ingredients.
  

To Prepare the Ingredients

• Peel 2 carrots with a vegetable peeler. Then, cut the carrots into thin, long strips with a julienne peeler. You can also julienne with your knife using the hosogiri cutting technique.
  
• Save any leftover pieces of carrot that you can't peel to use in another dish later. Place the julienned carrots in a microwave-safe bowl and cover with a damp paper towel.
  
• Cook the carrots in the microwave for 1 minute (1000W) to lightly soften them. Remove the paper towel and let cool.
  
• Thinly slice ½ red onion. Soak the sliced onion in a bowl of cold water to remove the bitterness.
  

To Make the Dressing

• Meanwhile, make the dressing. To a large mixing bowl, add 1 Tbsp extra virgin olive oil, 2 Tbsp rice vinegar (unseasoned), 1 tsp Dijon mustard, 1 tsp soy sauce, ⅛ tsp freshly ground black pepper, and ½ tsp Diamond Crystal kosher salt.
  
• Combine with a whisk. Cut the lemon in half (reserve the extra lemon for garnish). Squeeze 2 tsp lemon juice into the dressing and whisk again.
  

To Toss the Salad

• Drain 1 can albacore tuna (preferably packed in olive oil) and add the tuna to the bowl. Break it into small pieces and coat with the dressing.
  
• Then, add the cooled carrots and toss with the tuna.
  
• Squeeze the water from the onion slices and add them to the bowl.
  
• Add most of the ½ Tbsp toasted black sesame seeds to the bowl (reserving some for garnish) and give everything another toss.
  
• Cover the bowl and marinate the salad in the refrigerator for at least 1 hour. Transfer the Carrot and Tuna Salad to a serving plate.
  

To Serve

• Garnish with the remaining sesame seeds, optional lemon wedge, and optional parsley sprigs. Enjoy!
  

To Store

• Place the leftovers to an airtight container and store in the refrigerator for up to 3–4 days or in the freezer for a month.