In a small pot, cook lentils in broth until soft; about 20 minutes. Set aside.
Next, heat oil in a large frying pan. Add walnuts and mushrooms, and cook on medium heat for 2-3 minutes, stirring to prevent walnuts from sticking to the pan. Stir in green onions; heat 1 minute more. Add cooked lentils to the pan, followed by the salsa, tamari, smoked paprika, chili powder, and nutritional yeast. Cook for 5 minutes, allowing the spices to absorb and mushrooms to be tender.
Remove from heat; spoon onto tacos or use in burritos, on nachos, or in enchiladas. Sprinkle fresh cilantro on top before serving.