Preheat oven to 400°F. Combine sweet potato, 1 tbsp vegetable oil, and a pinch of salt and pepper on baking sheet and toss to coat. Arrange potato wedges in single layer and sprinkle with just half the breadcrumbs. Flip sweet potatoes over and repeat with remaining breadcrumbs. Bake until browned and crispy in places, 15 to 20 minutes. (TIP: Gently press roasted sweet potato into loose breadcrumbs.)

Meanwhile, stir together cucumber, radish, tamari, just half the vinegar, and a pinch of salt and pepper in medium bowl. Set aside until step 4.

Combine rice, 1 cup water, and a pinch of salt in small saucepan. Bring to boil over medium-high heat, cover, and reduce heat to low. Cook until water is absorbed and grains are tender, 12 to 18 minutes. Stir in remaining vinegar, sugar, and a pinch of salt and fluff with fork.

Arrange lettuce cups on serving plates and top with rice and crispy sweet potato. Using fork, lift pickles from ponzu brine and arrange on lettuce cups. Sprinkle with sesame seeds, as much nori as you'd like, and any breadcrumbs remaining on baking sheet. Drizzle with remaining ponzu brine. いただきます!

For 4-serving meal, double all ingredients. You may need to cook in batches, in larger cooking vessels, or for longer cook times. Follow visual cues in 2-serving recipe.