Somen noodles with Tomato mentsuyu (noodle soup base)

Combine mentsuyu, water, and tomato paste in a pot and mix well.

In a small pot, heat and bring to a boil.

Let the sauce cool.

Boil the somen noodles according to the package instructions.

Once the noodles are cooked, transfer them to ice water to cool. Serve them on a plate once chilled.

Add chopped green onion and sesame seeds to the cooled sauce, then serve with the chilled noodles.