Cold Tuna and Tomato Somen

1. Gather all the ingredients.

To Make Ahead (optional)

1. You can prepare the following steps several hours before you serve. In a medium bowl, combine 1 Tbsp rice vinegar (unseasoned) and 1 tsp sugar and whisk well.
2. To the bowl, add ½ (5-ounce) can albacore tuna (preferably packed in olive oil), including the oil. Mix well with the seasonings.
3. Cut 1 tomato into 8 wedges, then cut each wedge into 3 pieces (about ½-inch (1.3-cm) cubes).
4. Add the tomato cubes into the bowl and season with ⅛ tsp freshly ground black pepper and 2 tsp toasted sesame oil. Toss all together well and keep it chilled in the refrigerator.
5. Cut off the stems of 5 shiso leaves (perilla/ooba) and roll them up from the stem side. Cut them into thin julienned strips.
6. Fluff them up with your fingers and set them aside.
7. Make the noodle broth with ⅓ cup mentsuyu (concentrated noodle soup base) and 1 cup water. Keep it chilled in the refrigerator.

When You Are Ready To Serve

1. Bring a large pot of water to a boil. No need to salt the water for somen noodles. Once boiling, add 7 oz dried somen noodles so they are separated (as you would with spaghetti noodles). Cook according to the package instructions, usually 1½–2 minutes.
2. Keep stirring to make sure the noodles don‘t stick to each other. Control the heat so the water doesn‘t boil over.
3. Once the noodles are done, drain into the colander. Quickly run cold water over the noodles to cool a bit.
4. Once the noodles are cool to the touch, knead/rub the noodles between your hands several times under running water. This helps removing any excess oil from the noodles.
5. Drain well and serve onto individual plates.
6. Top the noodles with the tuna and tomato mixture.
7. Pour the broth over the noodles and garnish with shiso leaves.

To Store

1. If you have extra tuna and tomato mixture and broth (BEFORE serving), save them separately in airtight containers and store them in the refrigerator for 2–3 days. I recommend cooking noodles right before serving so they don‘t stick together.