Try this with other root vegetables.

1 lb (red) potatoes
1 lb carrots
2 T extra-virgin olive oil
1 t salt

Vinaigrette:
2 T extra-virgin olive oil
2 c thinly sliced red onions
1 t fresh thyme leaves, or 1/2 t dried
large pinch of salt
2 T red wine vinegar
1 1/2 T grainy mustard, or other mustard
1 T honey
2 T finely chopped fresh parsley
black pepper, to taste

1. Preheat the oven to 400ºF.

2. Scrub potatoes and quarter. Scrub carrots, (peel) and cut on the diagonal into 1/2-inch thick slices. Toss potatoes and carrots with the oil and salt. Spread vegetables in a roasting pan or on a rimmed baking sheet and roast until tender, about 30 minutes.

3. Meanwhile, make the vinaigrette. In a medium skillet heat oil over medium heat. Add sliced onions, thyme, and salt, and cook, stirring, until the onions are softened, about 5 minutes. Add the vinegar, mustard, and honey and stir well. Make sure honey has melted and is incorporated evenly into mixture. Take off heat–don’t let the vinegar evaporate.

4. Transfer the roasted vegetables to a serving bowl and pour over the onion mixture. Add the parsley, season with pepper, and toss well. Allow the vegetables to absorb the vinaigrette for at least 5 minutes before serving warm, or at room temperature.