For the tacos:

1. Toss the butternut squash with 2 tbsp olive oil, cumin, cinnamon, salt and pepper. Place squash on a large skillet over medium-high heat and cook until tender and browned, about 10-15 minutes.
2. In a large saucepan, add olive oil over medium heat. Once oil is hot, add chopped onion and cook for about 3 minutes. Add garlic, and let cook for another couple minutes, until fragrant and before browning.
3. Add crumbled tempeh, taco seasoning, lime juice, and stir to combine. Let cook for another couple minutes, remove from heat and add cilantro.
4. Place corn tortillas over an open flame (medium heat) on the stovetop. Let cook until tortilla begins to bubble and brown, less than a minute. Using tongs, flip over to cook the other side, until it begins to brown and bubble.
5. Assemble tacos by adding the tempeh mixture, butternut squash, and salsa verde. Top with a squeeze of lime and avocado slices.
6. Optional for vegetarians: add queso fresco and/or plain Greek yogurt as a topping.

For the Salsa Verde (adapted from Confessions of a Foodie):

1. Roast tomatillos, onion wedge, garlic, and jalapeno on a lightly greased skillet over medium-high heat. Using tongs, continue to rotate vegetables so that they’re blistered on every side. Roast until tender and blistered, about 10 minutes (note: tomatillos will take longer).
2. Transfer onion, pepper, garlic, and tomatillos to a food processor. Add lime juice and water. Pulse to combine until smooth. Add salt to taste. Transfer to a serving bowl and stir in chopped onion and cilantro.