Preheat the oven to 400°F. Wrap the beets in aluminum foil with a drizzle of olive oil and a pinch of salt and pepper. Place on a baking sheet and roast in the preheated oven until tender, about 45-60 minutes. Once done, remove from the oven, let cool, then peel and cut into bite-sized pieces.
While the beets are cooling, prepare the honey-balsamic dressing. In a small bowl, whisk together balsamic vinegar, olive oil, honey, Dijon mustard, salt, and pepper until well combined. Adjust the seasoning as needed.
In a large salad bowl, toss the mixed greens with a portion of the dressing until lightly coated.
Add the roasted beets, goat cheese, and walnuts to the greens. Drizzle with the remaining dressing and gently toss to combine. Season with additional salt and pepper if desired and serve immediately.