In a large bowl, stir together yogurt, vinegar, dill, sugar, salt and pepper. Set aside.
Heat wheat berries in a microwave-safe bowl for 2 minutes; stir and heat 1 more minute, until thawed.
Toss wheat berries, lentils, beets, lettuce, spinach and pistachios in bowl with dressing. Gently fold in salmon, if desired.
