- In medium saucepan, bring 2 inches water to boil over high heat.
- Place steamer basket in saucepan, add tempeh, cover and steam 20 minutes.
- Meanwhile, in large bowl, mix tamari, wasabi powder if using, and sesame oil.
- Add hot tempeh and mix well to coat.
- Set aside to marinate while preparing rice.
- In medium saucepan, bring 2 cups water to a boil.
- Add rice and salt and return to a boil.
- Cover, reduce heat to low and simmer until water is absorbed, about 35 minutes.
- Preheat oven to 375°F.
- Remove rice from heat and let stand, covered, 10 minutes.
- Transfer rice to large bowl and fluff with fork.
- Drain tempeh; spread on baking sheet.
- Bake, stirring occasionally, until lightly browned on all sides, about 25 minutes.
- Bring small saucepan of water to a boil.
- Add corn, cover and cook 2 minutes.
- Drain, rinse under cold running water and drain well.
- Set aside.
- In small bowl, whisk together vinegar and mirin.
- Gradually pour mixture over rice while still slightly warm and mix gently to combine.
- When rice reaches room temperature, add corn, mushrooms, radishes and tempeh and toss to blend.
- Break thick stems off watercress; discard.
- Break remaining watercress in half, wash, then dry thoroughly in salad spinner or with paper towels.
- In large bowl, toss watercress with peanut-miso dressing.
- Place rice salad and watercress on individual serving plates; garnish with carrots and daikon.
- Alternatively, if salad is part of a buffet, place rice salad and watercress side by side on large serving platter; arrange carrots and daikon on separate plate.