Preheat your oven to 375°F (190°C) and line a loaf pan with parchment paper.
In a large bowl, mash half of the cooked lentils until mostly smooth.
Add in the remaining lentils, walnuts, onion, celery, carrots, and garlic, mixing until well combined.
Stir in the breadcrumbs, flax eggs, tomato paste, soy sauce, thyme, and rosemary.
Press the mixture firmly into the prepared loaf pan.
Bake for 45 minutes, or until the loaf is firm and the top has a slight crust.
Let the loaf cool in the pan for 10 minutes before lifting it out onto a serving platter.
Slice and serve as a vegan alternative to traditional meatloaf, garnished with fresh herbs.