Place the Wheatberries and 3 cups of boiling salted water in a saucepan and cook, uncovered, over low heat for approximately 45 minutes, or until they are soft.
Saute the red onion in 2 tablespoons of olive oil over medium-low heat until translucent, approximately 5 minutes. Turn off the heat and add the remaining 4 tablespoons (1/4 cup) of olive oil and the balsamic vinegar.
In a large bowl, combine the warm Wheatberries, sauteed onions, scallions, red bell pepper, carrot, 1/2 teaspoon salt, and the pepper. Allow the salad to sit for at least 30 minutes for the wheatberries to absorb the sauce.