Rinse the red lentils thoroughly under cold water and set aside.
Dice the tofu into small cubes and chop the carrot, parsnip, celery, and onion into similar bite-sized pieces. Mince the garlic.
Heat the olive oil in a large pot over medium heat. Sauté the onion and garlic until they soften, about 2-3 minutes.
Add the carrot, parsnip, and celery, cooking them for another 3-4 minutes until they begin to soften.
Stir in the rinsed lentils, tofu cubes, diced tomatoes, bay leaf, and dried thyme. Pour in the vegetable broth.
Bring the mixture to a gentle boil, then reduce heat to a simmer. Cover the pot and let it cook for about 20-25 minutes, or until the lentils and vegetables are tender.
In the last 5 minutes of cooking, stir in the spinach until wilted.
Season with salt and pepper to taste. Remove the bay leaf before serving.
Ladle into bowls and enjoy your hearty, nutritious stew.