Bring a medium saucepan of water to a boil over medium-high heat. Add
Black Lentils (1/2 cup)
reduce the heat to low, and simmer, stirring occasionally, for 15-25 minutes, until the lentils are just tender. Drain, place them in a large, shallow bowl or platter, and cool slightly.
Meanwhile, whisk together
Red Wine Vinegar (3 Tbsp)
Dijon Mustard (1 tsp)
Kosher Salt (1/2 tsp)
Ground Black Pepper (1/4 tsp)
in a glass measuring cup, then add the
Olive Oil (1/3 cup)
in a steady stream, whisking constantly.
Shallots (1/2 cup)
, stir, and set aside for 10 minutes. Use a fork to lift the shallots from the dressing, and place them in a medium bowl.
Using a small serrated knife, peel the
and trim any remaining pith. Slice the oranges crosswise into thin circles about 1/4-inch thick, remove any visible seeds.
Add the oranges to the bowl with the shallots. Add the
Castelvetrano Olives (3/4 cup)
, toss gently, and set aside.
Radicchio (1 head)
to the platter with the lentils, drizzle with half the remaining dressing, and toss. Set aside until the lentils are completely cool. If using arugula, wait until just before serving to toss with the greens with the lentils and dressing.
Arrange the oranges, olives, and shallots over the radicchio, adding a few spoonfuls of the juices left behind in the dish.
Drizzle with more dressing to taste, top with the
Feta Cheese (1/2 cup)
Fresh Mint Leaves (to taste)
, and season with salt and pepper. Serve at room temperature.