RINSE wheat berries. Combine with 8 cups water in a medium pot. Bring to a boil over high, then reduce heat to medium-high. Cook, covered, until wheat berries are tender, 30 to 35 min. Stir in cranberries during the last 2 min of cooking. Drain and rinse with cold water.
WHISK oil with vinegar and salt in a large bowl. Season with pepper. Stir in wheat-berry mixture, kale, onion and pepper. Serve immediately. Keeps well, refrigerated, up to 1 day.