In a large pot or Dutch oven, heat the olive oil over medium heat.
Add the chopped onion, carrot, and celery (the mirepoix) and cook, stirring occasionally, until softened, about 5-7 minutes.
Add the minced garlic and cook for another minute until fragrant, being careful not to let it burn.
Stir in the rinsed lentils, vegetable stock, bay leaf, and thyme sprigs.
Season generously with salt and freshly ground black pepper.
Increase the heat to bring the soup to a boil.
Once boiling, reduce the heat to low, cover, and let it simmer gently for 30-40 minutes, or until the lentils are tender but not mushy.
Remove the pot from the heat. Fish out the bay leaf and thyme sprigs. If the soup is too thick for your liking, stir in a bit more vegetable stock or water until it reaches your desired consistency.
Taste the soup and adjust the seasoning with more salt and pepper if needed.
Serve hot, perhaps with a drizzle of olive oil and some crusty bread.
Stir in a few large handfuls of fresh spinach or chopped kale during the last 5 minutes of cooking for a boost of greens. A squeeze of fresh lemon juice at the end will brighten all the flavors.
Finish with a flourish! A drizzle of high-quality extra virgin olive oil, a dollop of vegan yogurt, or a sprinkle of fresh parsley just before serving adds a wonderful richness and fresh flavor.