Preheat oven to 400°F (200°C). Rinse beets, trim greens, and wrap each beet in aluminum foil. Roast on a baking sheet for 45–60 minutes, until very tender. Let cool, then peel and cut into wedges.

Segment the oranges

Peel the oranges and segment over a bowl to catch juices. Reserve the orange segments and squeeze any remaining juice from the membranes into the bowl for the dressing.

Toast the walnuts

In a dry skillet over medium heat, toast walnuts 4–5 minutes until fragrant. Remove from heat and roughly chop.

Prepare the greens

Rinse arugula (and spinach if using) and dry thoroughly using a salad spinner or clean towels to ensure crisp leaves.

Dressing

Whisk vinaigrette

In a small bowl, whisk together olive oil, red wine vinegar, orange juice, honey, salt, and pepper until emulsified. Taste and adjust seasoning as needed.

Assemble

Toss greens with dressing

In a large bowl, drizzle a portion of the vinaigrette over the arugula (and spinach) and toss to coat without wilting the leaves.

Add beets and oranges

Add the roasted beet wedges and orange segments to the greens. Gently toss to combine.

Finish with toppings

Crumble goat cheese over the salad, sprinkle the toasted walnuts, and scatter microgreens. Finish with chopped dill or chives if using.

Final touches

Season and serve

Season with additional salt and pepper to taste. Serve immediately on chilled plates for best color and texture.