Preheat oven to 425 F. Wrap beets in tin foil and roast for an hour. Remove from oven, unwrap and slice when they stop steaming.
Marinade:
Mix all marinade ingredients together in a bowl. Add tempeh pieces and marinade for an hour.
Preheat a large cast iron pan over medium-high heat. Remove tempeh from marinade and saute in a little olive oil or cooking spray. When they’re browned (about 7 minutes) splash in some extra marinade and toss to coat. Remove from heat.
For the Maple Mustard Dressing:
Mix everything together in a bowl. When ready to serve, microwave for 30 seconds or gently heat in a pan over low heat.
To assemble:
Place the greens in a super large mixing bowl. Drizzle in the dressing and use tongs to coat. The greens will wilt slightly.
Transfer salads to 4 plates (or two, if you’re looking for entree-sized salads). Place slice beets snugly against the greens. Scatter on tempeh croutons and a few slices of sliced red onion.