1 Rinse the green beans and combine in a pot filled with a little lightly salted water. Bring to a boil, reduce to a simmer, cover and cook until bright green and crisp-tender, 12-14 minutes.
2 Meanwhile, whisk together the wasabi powder, apple juice, and 2 tablespoons hot water in a bowl. Season with salt and pepper, then whisk in the oil to make a sauce.
3 Rinse the scallion, wipe dry and cut into thin rings. Cut the apple into quarters, core, peel and cut into small dice.
4 Mix the diced apple and scallion into the sauce.
5 Drain the green beans and mix with the sauce. Allow to cool.
6 Rinse the celery, remove any strings and cut stalks into thin slices.
7 Drain the herring fillets and cut into strips. Toss the celery and herring with the green beans and let stand for about 30 minutes.
8 Cut the cress from the roots. Season the herring-bean salad again with salt and pepper, sprinkle with cress and serve.