⅓ cup fresh celery juice (from about 2 stalks)
⅓ cup fresh sorrel or cilantro juice (from about 2 cups, lightly packed)
2 teaspoons fresh leek juice (from about 1 dark-green leek top)
1 tablespoon white wine vinegar or fresh lemon juice
1 pound baby potatoes
3 tablespoons olive oil, divided, plus more for drizzling
4 4-oz. pieces skin-on hake or cod fillet
4 scallions, trimmed
½ cup plain Greek yogurt
Chervil or other tender herb sprigs (for serving)
For green sauce - combine celery juice, sorrel juice, leek juice, and vinegar in a small bowl; season with salt and more vinegar, if desired. DO AHEAD: Green juice without vinegar can be made 6 hours ahead. Cover and chill. Stir in vinegar just before serving.
For potatoes - place potatoes in a medium saucepan and add water to cover; season with salt. Bring to a boil, reduce heat, and simmer until tender, 10–15 minutes; drain and return to saucepan. Toss potatoes with 1 Tbsp. oil, then season with salt.
For fish - heat 1 Tbsp. oil in a large skillet over medium-high heat. Season fish with salt and cook, skin side down, until very crisp, about 4 minutes. Turn fish and cook until just cooked through, about 2 minutes longer. Transfer to a plate. Heat remaining 1 Tbsp. oil in same skillet and add scallions. Cook, turning occasionally, until scallions are charred in spots and are slightly softened, about 1 minute. Transfer to plate with fish.
Divide fish, yogurt, and potatoes among shallow bowls. Spoon green sauce around and drizzle with oil. Top with scallions and chervil.
CREDITS: JJ Goode