1 large onion, quartered through root end

2 bay leaves

1½ C black beluga or French green lentils, rinsed, picked through

Kosher salt

¼ cup olive oil

1 t coriander seeds

½ t cumin seeds

3 T sherry vinegar or red wine vinegar

Freshly ground black pepper

6 radishes, trimmed, very thinly sliced

4 scallions, thinly sliced

1 C parsley and/or mint leaves

1 C thinly sliced celery hearts and leaves

Cook onion, bay leaves, and lentils in a large saucepan of simmering salted water until lentils are tender but still firm, 15–20 minutes. Drain; discard onion and bay leaves and transfer lentils to a medium bowl.

Heat oil in a small skillet over medium. Cook coriander seeds and cumin seeds, swirling skillet, until fragrant, about 1 minute. Add spice mixture and vinegar to lentils, season with salt and pepper, and toss to coat.

Just before serving, top lentils with radishes, scallions, herbs, and celery; season with salt and pepper.

Do Ahead: Lentils (without herbs and vegetables) can be marinated 3 days ahead. Cover and chill.