Press the tofu between 2 pieces of paper towel to remove excess moisture. Place the tofu on a plate with the mushrooms. Spray with oil and sprinkle over Cajun seasoning. Turn to coat tofu and mushrooms.

Heat a small nonstick skillet over medium-high heat. Add the tofu and mushrooms. Cook tofu for 3 minutes on each side, until warmed through and starting to turn a golden brown. Cook mushrooms for 2 minutes, until golden. Remove from heat.

Spread mayo on the bottom half of the bun. Top with lettuce, tofu, mushrooms, carrot and beets. Add top half of bun and serve.

TIP: This can be enjoyed warm, or alternately, allow the tofu to cool, construct the burger and pack it into a lunch box for work.