Put the walnuts and sundried tomatoes in blender and pulse until combined. Set aside.
In a large skillet, saute diced red onion in vegan butter until softened - about 5 minutes. Add in diced mushrooms and saute until cooked through. Add in the walnut/sun dried tomato mixture and heat through. Add the cooked lentils and spices and stir to combine/heat through. Play with the seasonings until it is how you want it.
While this cooks, make your Spicy Aioli. Mix 1/4 cup of Vegenaise, sriracha to taste and a juice of one half lemon. Mix thoroughly.
To plate, for each taco. Spread "meat" mixture on Romaine Lettuce Leaf (or in wrap of your choice), top with fresh pico de gallo, avocado and spicy aioli sauce.