Step 1

Using the side of a chef’s knife, crush Sichuan peppercorns until coarsely ground. (You can also do this in a spice mill if you have one.) Transfer to a small heatproof bowl and add scallions, garlic, sesame seeds, and red pepper flakes.

Step 2

Heat oil in a small heavy saucepan until the first sign of smoke. Using a towel to hold the handle, immediately pour oil into bowl with Sichuan peppercorn mixture. (This technique releases the flavors of the aromatics without burning them.) Stir in tamari and vinegar and season dressing with salt; let cool.

Step 3

Cook corn in a large pot of boiling generously salted water until bright yellow and tender, about 30 seconds. Using a slotted spoon, transfer to a large bowl of cold water and let cool.

Step 4

Cook green beans in same pot of water until bright green and tender, about 1 minute. Using slotted spoon, transfer to bowl with corn and let cool. Drain; set vegetables aside.

Step 5

Return water in pot to a boil and cook noodles according to package directions. Drain and rinse under cold running water; drain well.

Step 6

Combine noodles and reserved corn and green beans in a large bowl. Drizzle in ½ cup dressing and toss to coat. (You can add more dressing if desired; reserve any leftovers for another use.)Do ahead: Dressing can be made 3 days ahead. Cover and chill.