This is a colourful, healthy and tasty variation of the picnic classic: three-bean salad.
Bring a pot of salted water to a ful boil and blanch the green beans until tender, about 4 minutes. During the last minute, add the edamame. Drain the beans and rinse to cool.
Toss the green beans and edamame with the black beans and red onion.
For the dressing, whisk the lemon juice, tahini paste, garlic and oregano together. Drizzle in the olive oil while whisking and season to taste. Toss the beans with the dressing and sesame seeds and season again, if needed. Chill the salad until ready to serve.
The salad can be assembled up to six hours of serving.