Green Salad with Roasted Beets and Pickled Rhubarb

Name: Green Salad with Roasted Beets and Pickled Rhubarb
Ingredients: 3 medium golden beets (1 pound total); 5 tablespoons extra-virgin olive oil; Kosher salt and freshly ground pepper; 3 to 4 pieces Pickled Rhubarb, thinly sliced on the bias (1/2 cup), plus 2 tablespoons pickling liquid; 2 teaspoons Dijon mustard; 2 tablespoons chopped fresh dill or mint, plus more sprigs or leaves for serving; 2 to 3 heads Little Gem lettuce, or 1 to 2 small heads Boston or Bibb lettuce, torn into bite-size pieces (8 cups)