Preheat your oven to 400°F (200°C). Wash the beets thoroughly and trim off the tops and roots. Place them on a sheet of aluminum foil, drizzle with a tablespoon of olive oil, and wrap them completely. Place on a baking sheet and roast until tender when pierced with a fork, approximately 45-60 minutes.
Once the beets are roasted, remove from the oven and let them cool until you can handle them. The skins should slip off easily when rubbed with a paper towel. Slice the peeled beets into bite-sized wedges or cubes.
While the beets are cooling, toast the walnuts in a dry skillet over medium heat for 5-7 minutes, stirring frequently to prevent burning. Remove from heat and let cool before roughly chopping.
In a small bowl, whisk together olive oil, balsamic vinegar, honey (if using), salt, and freshly ground black pepper until well combined.
Place mixed greens in a large salad bowl. If using red onion or orange segments, add them now. Drizzle about half of the dressing over the greens and toss gently to coat.
Arrange the roasted beet pieces on top of the dressed greens. Crumble the goat cheese over the salad and sprinkle with the toasted walnuts. If using fresh thyme, add it now.
Drizzle the remaining dressing over the completed salad. Serve immediately at room temperature for the best flavor experience.
