Press the firm tofu to remove excess moisture, then cut into bite-sized half-inch cubes.
Heat the olive oil in a medium pot over medium heat.
Add the diced onion, carrots, and celery to the pot and sauté for 5 to 7 minutes until the vegetables begin to soften.
Stir in the cubed tofu, dried oregano, garlic powder, sea salt, and black pepper, cooking for 3 minutes to allow the tofu to absorb the flavors.
Pour in the vegetable broth and bring the liquid to a gentle boil.
Add the dry rotini pasta and cook according to the package instructions, typically 8 to 10 minutes, until al dente.
Reduce the heat to low and stir in the nutritional yeast and fresh spinach, stirring until the spinach is just wilted.
Taste and adjust seasoning if necessary, then ladle the soup into a large bowl and enjoy immediately.