Place the lentils and vegetable broth in a medium pot and bring to a boil. Reduce heat to low and cook for about 20 minutes, until the lentils are soft, but not mushy.
In a non-stick or stainless steel skillet, sauté the diced onion until it becomes translucent. Add a small amount of water to the pan if it begins to stick.
Add in the garlic and sauté for another minute, until the garlic is fragrant.
Add the walnuts, and sauté for a few minutes to toast them. Then add the spices and tomato paste, and stir to coat the onions and walnuts.
Mix in the lentils and cook briefly. If there is liquid left from cooking the lentils, simmer until the liquid is evaporated. If the mixture is too dry, add a small amount of water.
Cooking longer will result in mushier lentils, more like the texture of refried beans.
