Preheat oven to 400°F.: You will notice the oven warming and a faint dry heat that helps caramelize the surface of the beets . Preheating ensures even roasting and encourages the natural sugars to deepen in flavor. A common mistake is not waiting for the oven to reach temperature, which can lead to uneven doneness. Make sure your oven reads the full 400°F before sliding the tray in.
Cook the beets: Line the bottom of a baking sheet with aluminum foil. Wrap each beet tightly in foil (like you would a baked potato) and arrange on the baking sheet. Bake for 1 hour, or until the largest beet is easily pierced with a fork.: Wrapping each beet tightly in foil and placing them on a lined baking sheet traps steam, so the vegetables roast while staying moist, producing tender flesh that is easy to pierce. You should hear a quiet settling sound as the beet juices concentrate, and smell a warm, earthy aroma as sugars caramelize. The reason we wrap them is to prevent drying out, the result is a silky interior. Avoid the mistake of crowding the pan, which can extend cooking time, and always test the largest beet with a fork to confirm tenderness.
Cool, peel, and cube the beets: Unwrap the beets and allow them to cool until they are easy to handle. Peel the skin off the beets and cube.: After removing the foil, let the beets cool until they are safe to handle; the skins should slip off with little resistance. As you peel, you may notice a faint steam and a sweet, roasted scent. Cube the beets into even pieces so each bite has consistent texture. If you rush peeling while too hot, you risk burning your fingers or tearing the flesh, so allow adequate cooling time to avoid damage.
Toss the salad: In a large serving bowl, add 6 cups arugula and toss with balsamic vinaigrette. Add the cubed beets, 1/2 cup feta or goat cheese, 1/2 cup pecans, and 1/2 cup cranberries, if desired. Toss again and serve.: In a large serving bowl, add the measured arugula and toss with the prepared balsamic vinaigrette so the leaves are lightly coated and glossy. Then incorporate the cubed beets , crumbled feta , pecans , and dried cranberries if using, tossing gently to combine without bruising the greens. You should see a glossy sheen on the leaves and smell the tang of balsamic vinegar mingling with the roasted sweetness. A typical pitfall is overdressing the greens making them soggy, so start with a modest amount of vinaigrette and add more if needed.
Combine: Combine 1/2 cup olive oil, 1/4 cup balsamic vinegar, 2 tablespoons honey, 1/2 tablespoon dijon mustard, 1 teaspoon garlic, 1/4 teaspoon salt, and 1/4 teaspoon pepper in a mason jar. Whisk or shake until well combined.: Whisk olive oil , balsamic vinegar , honey , dijon mustard , minced garlic , salt , and black pepper in a jar until the mixture is emulsified and slightly thickened, then taste and adjust seasoning. The smell should be bright and slightly sweet, with the garlic providing a savory undercurrent. Emulsifying helps the dressing cling to the beets and greens; if it separates, shake again just before serving. Avoid adding too much salt at once, as the feta and pecans contribute saltiness to the finished salad.