Blend the walnuts into a coarse flour. Pour that flour into a medium bowl.
Add half of the lentils and the mushroom mixture, salt, spices, and flax mixture. Mix everything until it’s well combined and forms a thick dough using a hand blender. Then, stir in the remaining whole lentils.
Using wet hands, form into 12-15 little cakes.
Put cakes on a baking sheet with a little oil. Bake them in a 375 degree oven for 10-15 minutes or until they form a crust, before flipping. Cook them for 5 more minutes on the other side.
Pour all the ingredients into a heated pan, whisking all the time until thickened, about 3-5 minutes, then remove from heat.