Prepare dressing. Combine balsamic vinegar, honey, mustard, and garlic in a small bowl. Slowly add the olive oil, whisking continuously. Add salt and pepper to taste.
Roast beets. Preheat oven to 375ºF. Place unpeeled beets in a baking dish, add water to cover ¼” of the bottom of the beets, then cover with foil. Bake until easily pierced with a fork. Cook time will depend on the size of the beets; plan on ~40 minutes for a large beet. Cool slightly, then peel and dice into ½” pieces.
Roast walnuts. Place walnuts in a single layer on a sheet pan. Bake for 8-10 minutes or until fragrant and golden brown. Add them to the oven with the beets during the last 8 minutes to save time!
Place all salad ingredients in a medium bowl or on your dinner plate. Have fun composing artistically or toss to combine with the dressing. Enjoy!