Bring a large pot of water to a boil. Cook the soba noodles according to package directions, usually 4 to 5 minutes. Do not overcook them; soba gets mushy fast. Drain immediately into a colander and rinse thoroughly under cold running water for about 30 seconds until the noodles are completely cooled.

Shake off as much water as possible, then transfer the noodles to a large mixing bowl. Drizzle the 1 teaspoon of sesame oil over them and toss to coat. This keeps them from sticking together while you make the sauce.

In a small bowl, whisk together the peanut butter, soy sauce, sriracha, rice vinegar, sesame oil, honey, and garlic. Add the warm water one tablespoon at a time and whisk until the sauce is pourable but not watery. Taste it and adjust sriracha or soy sauce if needed.

Pour the peanut sauce over the noodles and toss until every noodle is coated. The sauce should look glossy and generous.

Add the shredded chicken and thawed edamame to the bowl and fold everything together until evenly distributed.

Divide the noodle mixture evenly among four containers. Top each with sliced green onions and sesame seeds if using.

Seal and refrigerate. Eat cold straight from the container, or stir in a tablespoon of warm water before eating if the noodles have absorbed most of the sauce overnight.