Pickled Vegetable Salad with Nori
6 radishes, trimmed, thinly sliced
2 large carrots, peeled, julienned
½ medium red onion, thinly sliced
½ English hothouse cucumber, thinly sliced
2 tablespoons sugar
1 tablespoon kosher salt
1¼ cups unseasoned rice vinegar, divided
2 toasted nori sheets
¼ cup vegetable oil
2 tablespoons reduced-sodium soy sauce
1 tablespoon mirin (sweet Japanese rice wine)
5oz. 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 ¼ 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.