Rinse rice and wheat berries and soak, covered, in water 6 hours or overnight.

After soaking, place rice, wheat berries and 2 cups water in a large heavy pot, cover and place over medium low for 20 minutes.

Turn the heat to high and, when steam begins to escape from the lid, turn heat to medium low.

Simmer for 50 minutes.

Remove from heat and let sit, covered, for 5 to 10 more minutes.

Meanwhile, prepare the vegetables.

Preheat the oven to 450°F.

Place onion, turnips, carrots and butternut squash in a large bowl.

Add 2 tablespoons olive oil, herbs, 1 teaspoon salt and 1/2 teaspoon pepper and toss to coat evenly.

Spread vegetables on two rimmed baking sheets and roast for 20 minutes, stirring halfway through.

Toss mushrooms with 1/4 teaspoons olive oil and add to one of the roasting pans.

Roast vegetables for 15 minutes, until tender enough to be pierced with a fork.

To make the vinaigrette, whisk together 6 tablespoons olive oil, 1/4 teaspoon pepper, salt, white wine vinegar, mustard, and garlic.

When grains are cooked, mix half the vinaigrette with warm grains.

Combine vegetables with grains and mix in remaining vinaigrette.

Serve warm or at room temperature.