Using your circular ring mold, carefully cut out circles in the four pieces of pressed tofu. Set aside. In a large pyrex dish, combine all of the ingredients for the marinade. Place the tofu into the marinade, flipping over once to ensure its well coated. Place in the refrigerator for at least 4 hours, flipping again halfway through the marinade time.
Preheat oven to 400 degrees. Boil 1 1/4 cups water in a small saucepan. Place the cubed beets in the boiling water for about 5 minutes. Transfer the beets with a slotted spoon to a well-greased baking pan, adding 2 TB of the oil to coat. Bake for 25 minutes. Add the diced red onion to the beet mixture with the remaining 1 TB oil and place back into the oven for 25 minutes more, stirring occasionally to prevent scorching.
Once you've added the red onion to the beets, make your couscous by placing the couscous into the beet infused water and bring to a boil. Reduce the heat and cover. Simmer over low heat for about 30 minutes.
Once your beets and couscous are done, remove the tofu from the refrigerator and saute over medium high heat in a large skillet until well-browned, about 5-7 minutes on each side. Remove from the heat and add the asparagus to the pan. Saute until bright green, about 6 minutes.
Place the remainder of the marinade into a small saucepan over medium high heat until it slightly thickens and reduces. Remove from heat and let it cool slightly while you plate.
To assemble the tower, place a ring mold onto a plate and add a slice of the tofu. Spoon some of the beet mixture over than, lightly but firmly packing it into place. Add another slice of tofu and then add a layer of the couscous on that, packing it lightly but firmly. Top with another slice of tofu and carefully remove the ring.
Serve with the sauteed asparagus and spoon some of the reduced balsamic marinade over the top.