Sort and rinse 1 cup of green or brown lentils under cool water. Combine with 3 cups of vegetable broth in a medium saucepan. Bring to a boil, then reduce heat and simmer for 40 minutes until mushy. Mash slightly and cool.

Finely chop one medium carrot and add to a large mixing bowl. Chop half a cup of walnuts and mix with the carrots.

Heat 2 tablespoons of olive oil in a skillet. Add one chopped onion and sauté for 2-3 minutes until translucent. Stir in 2 minced garlic cloves, 1 cup chopped celery, 1 teaspoon dried thyme, and 1 teaspoon ground paprika. Sauté for 2 more minutes.

In a large mixing bowl, combine sautéed vegetables with mashed lentils. Stir in Bragg's Liquid Aminos, nutritional yeast, oat flour, and ground flax seeds mixed with water. Season with salt. Mix until incorporated.

Line a 9x5 loaf pan with parchment paper. Pack the lentil mixture tightly into the pan, smoothing the top.

In a medium bowl, whisk together tomato paste, water, maple syrup, lemon juice, molasses, garlic powder, onion powder, allspice, and salt. Pour into a saucepan and heat for 5 minutes until thickened.

Preheat your oven to 375°F (190°C). Pour the ketchup glaze over the packed lentil loaf. Bake for 45-50 minutes until edges brown and glaze caramelizes. Cool for 30 minutes before slicing.