This warm one-pot meal is full of hearty root vegetables like sweet potatoes, carrots and beets that pack fiber and cancer-fighting carotenoids. Roasting gives them a slightly sweeter flavor that pairs nicely with this tangy Dijon dressing.
Preheat oven to 425 degrees. In large bowl toss potatoes, carrot, onion, celery and beet with 1/2 tablespoon oil, coating well. Arrange vegetables in a roasting pan. Season with salt and pepper. Roast, stirring several times, until tender and beginning to brown, about 50 minutes.
In mixing bowl, whisk vinegar, lemon juice and Dijon with remaining oil and stir in parsley, cilantro and walnuts. Drizzle dressing over vegetables and gently toss. Top with crumbled feta. Serve warm or at room temperature.