Step 1

Line a fine-mesh strainer with cheesecloth and fit over a medium bowl. Place 2 pounds tomatoes in a blender. Turn the blender on to low speed and slowly increase up to high speed. Blend until very smooth, about 1 minute once on the highest speed. Pour the tomato pulp into the strainer and let sit until the bowl has collected about 2 cups tomato water, about 2 hours. Meanwhile, prepare the vegetables.

Step 2

Cut the whites from 4 medium scallions into 1/2-inch pieces, then thinly slice the greens, keeping the whites and greens separate. Peel a 2-inch piece of ginger and finely chop until you have 1 tablespoon. Finely chop 2 garlic cloves. Dice 8 ounces cucumber.

Step 3

When the tomato water is ready, discard the contents of the strainer. Add 2 teaspoons kosher salt to the tomato water and stir to dissolve.

Step 4

Heat 2 tablespoons vegetable oil in a large skillet over medium-high until shimmering. Add the scallion whites and chopped ginger and cook until the scallions begin to look translucent, about 2 minutes. Add the garlic and 2 cups cherry tomatoes, and cook until the tomatoes start to burst, about 5 minutes. Stir in the cucumbers, then remove from the heat. Let cool until room temperature, about 20 minutes. Meanwhile, cook the noodles.

Step 5

Bring a large pot of heavily salted water to a boil. Add 1 (6 1/2-ounce) package soba noodles and cook according to package directions. Drain the noodles and run under cold water until cool. Drain again. Drizzle with 1 tablespoon toasted sesame oil and toss to combine.

Step 6

To serve, divide the soba between 4 bowls. Divide the vegetable mixture over the noodles. Top with the scallion greens and drizzle each bowl with 1/4 teaspoon Asian chili oil, if desired. Pour the tomato water into the bowls and serve immediately.