Preheat oven to 450°F.

Make Vinaigrette: In a large bowl, place Dijon mustard, ½ teaspoon salt and ¼ teaspoon pepper. Whisk to combine, and slowly stream in oil, whisking continuously until emulsified.

Add all of the vegetables to the bowl and toss with the vinaigrette. Pour into the bottom of a large roasting pan. Scatter thyme sprigs over top.

Rinse the chicken and pat dry with paper towels. Generously salt and pepper the entire chicken - both outside and in the cavity. Truss the chicken and place on top of the vegetables in the roasting pan.

Place the pan into the preheated oven and let the chicken and vegetables roast for about an hour, or until the internal temperature reaches 165°F and the juices run clear. Remove the chicken to a cutting board and let rest at least 10 minutes.

Carve chicken and serve on top of roasted veggies, seasoning with a little more salt and pepper if needed. Enjoy!