Preheat your oven to 400°F (200°C). Scrub and peel the beets, then cut them into wedges. Drizzle with olive oil and sprinkle with salt.

Spread the beets on a parchment-lined baking sheet and roast for 25-30 minutes, flipping halfway through.

Once roasted, let the beets cool for about 10 minutes and then slice them into thin wedges.

Toast the walnuts in a dry skillet over medium heat for 3-5 minutes until fragrant.

Whisk together olive oil, balsamic vinegar, Dijon mustard, honey, salt, and pepper in a small bowl.

In a large mixing bowl, add arugula and drizzle half of the dressing over it, tossing gently.

Top the arugula with roasted beets, crumbled feta, red onion, and toasted walnuts. Add avocado if using.

Drizzle the remaining dressing over the salad and serve immediately.