1/3 cup unseasoned rice vinegar 1/3 cup vegetable oil 1 tablespoon Sriracha (hot chili sauce) 1 tablespoon toasted sesame oil 8 cups matchstick-size pieces mixed summer vegetables (such as carrots, radishes, cucumbers, and bell peppers; about 1 1/4 pounds) Kosher salt, freshly ground pepper 8 ounces buckwheat soba (Japanese-style noodles) or vermicelli noodles 1 cup (loosely packed) cilantro leaves with tender stems 3 scallions, thinly sliced 1 tablespoon black or white sesame seeds Whisk first four ingredients in a large bowl. Add vegetables; toss to coat. Season with salt and pepper. Cook noodles in a large pot of boiling salted water, stirring occasionally, until al dente; drain. Run noodles under cold water to cool them; drain well and add to bowl with vegetables. Add cilantro and scallions; season to taste with salt and pepper. Sprinkle sesame seeds over and serve.