Bring a large pot of salted water to a rolling boil, then add the soba noodles. Cook according to the package directions, usually around four to five minutes, since these noodles cook much faster than regular pasta. Drain them right away and rinse under cold water to stop the cooking and wash off extra starch.
While the noodles cook, whisk together the cashew butter, rice vinegar, tamari, sesame oil, honey, ginger, and garlic in a bowl. Keep whisking until the mixture turns smooth and glossy. If it feels too thick to pour, stir in a tablespoon or two of water until it loosens to a pourable consistency.
In a large bowl, combine the cooled noodles with the cabbage, carrots, bell pepper, edamame, and cilantro. Pour the dressing over everything and toss well so each strand of noodle gets coated. Finish with a sprinkle of toasted sesame seeds and any extra garnish you like.
Give the salad about fifteen minutes to sit at room temperature before digging in. This short rest lets the dressing soak into the noodles and vegetables, which noticeably improves the flavor. If you're short on time, it still tastes great right away, just slightly less deep in flavor.