In a small pot, add lentils and ½ cup water. Bring to boil, and reduce heat to a medium-low.
Add bay leaf, salt, pepper, and simmer for 5 minutes. Add 1 cup of water and continue to simmer for 15 more minutes. Stir every 5 minutes.
Once lentils are done, they should be soft and water fully absorbed. You can simmer them for 3-5 more minutes if lentils are hard; be careful not to overcook them. Once they are done, transfer them into a deep bowl and set aside. Remove the bay leaf.
Place the walnuts into the mortar. Evenly crush them into smaller pieces. Alternatively, you can chop walnuts with a knife.
Next, prepare the onion mix. Heat medium pan over low heat. Add 3 Tablespoons of butter, chopped onions, and cumin seasoning.
Cook them slowly for 10 minutes, stirring every few minutes.
Remove onions from the heat and set aside.
Transfer lentils to the food processor (or blender), add 3 Tbsp water and onions. Process this mixture,adding a few cubes of butter at a time, until all of the butter has been incorporated and the pate is smooth. Scrape the sides of the food processor down if necessary.
Fold in crushed walnuts. Taste the pate and add more salt and pepper if needed.
Transfer the pate into an airtight container and refrigerate for 3 hours before serving. Enjoy with favorite whole grain bread, on toasted bread, or crackers. Keep refrigerated up to 5 days.