Heat olive oil in a large pot or Dutch oven over medium heat. Add the onion, carrots, and celery, and cook until softened, about 5-7 minutes.

Add the minced garlic and cook for another minute until fragrant.

Stir in the rinsed lentils, quinoa, vegetable broth, diced tomatoes, optional tofu cubes, nutritional yeast, dried thyme, dried rosemary, and bay leaves. Season with salt and pepper to taste.

Bring the mixture to a boil, then reduce the heat to low, cover, and let it simmer for 40-50 minutes, or until the lentils and quinoa are tender. Check at 40 minutes as red lentils cook faster than brown.

After the stew has been simmering for about 25 minutes, start preparing the mashed potatoes. Place the peeled and cubed potatoes in a large pot and cover with salted water. Bring to a boil and cook for 15-20 minutes, or until the potatoes are fork-tender.

Drain the potatoes thoroughly and return them to the hot pot (the residual heat helps excess moisture evaporate). Add the Greek yogurt, butter, protein powder, salt, and pepper while still steaming. Mash until smooth and creamy.

Once the lentil stew is done, remove the bay leaves. Taste and adjust the seasoning if necessary. Let rest for 5 minutes to allow flavors to meld.

To serve, place a scoop of protein-enhanced mashed potatoes in a bowl and ladle the hot lentil stew over the top.