- 6 radishes, trimmed, thinly sliced
- 2 large carrots, peeled, julienned
- 1/2 medium red onion, thinly sliced
- 1/2 English hothouse cucumber, thinly sliced
- 2 tablespoons sugar
- 1 tablespoon kosher salt
- 1 1/4 cups unseasoned rice vinegar, divided
- 2 toasted nori sheets
- 1/4 cup vegetable oil
- 2 tablespoons reduced-sodium soy sauce
- 1 tablespoon mirin (sweet Japanese rice wine)
- 5 ounces tender lettuces (such as Bibb, butter, and mâche; about 6 cups)
- Place radishes, carrots, onion, and cucumber in 4 separate bowls or jars. Bring sugar, salt, 1 cup vinegar, and 2 cups water to a boil in a medium saucepan, stirring to dissolve sugar. Pour pickling liquid over vegetables to cover; let cool. Cover and chill.
- Grind nori in a blender, scraping down sides as needed, until finely ground. Add oil, soy sauce, mirin, and remaining 1/4 cup vinegar and blend until smooth. Toss lettuces and dressing in a large bowl to coat. Drain pickled vegetables and arrange on top of salad.
- DO AHEAD: Nori vinaigrette can be made 3 days ahead; cover and chill. Vegetables can be pickled 1 day ahead; keep chilled.