What makes this dish unique is the use of whole grain mustard to dress the vegetables. After being roasted, the mustard seeds become deeply caramelized or charred and create the most delicious crunch.
- ¼ cup whole grain mustard
- ½ tablespoon white wine or champagne vinegar
- ¾ teaspoon salt
- 2 tablespoons olive oil (and more for the pan)
- 5 small beets, cut into eighths
- 1 large red onion, cut into thick crescents
- 2 tablespoons tarragon, roughly chopped (and more for garnish)
Preheat the oven to 500 degrees. Put a drop of olive oil on a rimmed baking sheet and place in the oven, while it preheats.
In an empty jar, combine the mustard, vinegar, salt, and olive oil, and shake vigorously until combined. Place the beets, onions, and tarragon in a large bowl. Pour in the dressing, and mix everything together with clean hands. Remove the hot baking sheet from the oven, and carefully pour the vegetables into a single layer. (Do not overcrowd the pan, as this will limit carmelization.)
Roast the vegetables at 500 degrees for 15 minutes, flip the vegetables, then reduce the temperature to 375 degrees, and cook for another 30-40 minutes until browned and tender. Garnish with additional fresh tarragon.