Press the extra firm tofu to remove excess moisture, then cut into small 1/2-inch cubes.
Heat olive oil in a large pot over medium heat and sauté the tofu until the edges are golden and crisp.
Add the diced onion, carrots, and celery to the pot, cooking for 5 minutes until the vegetables begin to soften.
Stir in the minced garlic, turmeric, and cumin, toasting the spices for 1 minute until fragrant.
Rinse the red lentils under cold water and add them to the pot along with the vegetable broth.
Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 15-20 minutes until the lentils are tender.
Stir in the nutritional yeast, sea salt, and black pepper to enhance the savory flavor profile.
Fold in the baby spinach during the last minute of cooking until it is just wilted and bright green.