Add 2 Tablespoons balsamic vinegar, 1 teaspoon granulated sugar, ½ teaspoon dijon mustard, ½ teaspoon kosher salt, and ¼ teaspoon freshly ground black pepper to a small bowl, measuring cup, or immersion blender blendering cup. Whisk or blend until uniform, then continue whisking/blending while you slowly pour in ¼ cup olive oil. The dressing will become quite thick. Set it aside for now.
Arugula Salad with Root Vegetables and Lentils
Toss the cut carrots with 1 Tablespoon olive oil, ¼ teaspoon kosher salt, and ¼ teaspoon freshly ground black pepper. Air fry or roast the carrots on a baking sheet at 400°F until tender and browned on the edges, about 20 minutes, stirring the carrots halfway through the cooking time. When the carrots are done, toss them with 1 Tablespoon of the balsamic dressing.
While the carrots are cooking, cook the lentils. Add ½ cup black lentils to a small saucepan with ¼ teaspoon kosher salt. Add just enough cold water to the saucepan to cover the lentils. Bring the water to a boil over high heat, then reduce to medium-low and simmer until the lentils are tender, but intact, about 20 minutes. Make sure to check the water level during cooking so that it doesn't get too low (adding too much water will cause the lentils to lose their color). Rinse and drain the lentils and toss them with 1 Tablespoon of the balsamic dressing.
Add 5 ounces baby arugula to a large bowl, then drizzle the remaining balsamic dressing over it. Toss the arugula until it's evenly coated with the dressing. Distribute the dressed arugula evenly between 2 (for entree-sized portions) to 4 (for side-sized portions) bowls.
Top the arugula in each bowl with equal portions of the cooked lentils, then the roasted carrots, followed by equal portions of each of the ½ cup cubed pickled beets, ¼ cup coarsely chopped almonds, and 2 ounces crumbled Feta cheese. Serve immediately.
Notes
If you don't have access to pickled beets, you could replace them with cubed roasted beets, though the finished salad won't be quite as flavorful.