Preheat oven to 375 degrees F (190 C). Add cubed butternut squash to a baking sheet and drizzle with oil, and add the spices. Toss to combine, then bake for 15-20 minutes, or until tender.
Add beans to a small saucepan over medium-low heat and cook until bubbly, then turn off heat and cover to keep warm.
In the meantime, prepare sauce. Heat large skillet over medium heat. Once hot, add oil, onion, and garlic. Cook, stirring frequently, until soft and slightly browned and translucent - about 4-5 minutes.
Turn heat to low and add tomato sauce, diced chipotle pepper, adobo sauce, water, cumin, chili powder, and coconut sugar. Stir to combine and simmer for 5 minutes.
Transfer sauce to a blender and blend well for a completely smooth sauce. Taste and adjust seasonings as needed, adding more adobo sauce for heat, water to thin, or coconut sugar for sweetness. Set aside.
Once the butternut squash is nearly done roasting, heat a large skillet over medium-high heat. Once hot, add 1 Tbsp oil (amount as original recipe is written // adjust if altering batch size) and portobello mushrooms. Sauté for 3-4 minutes, or until softened and browned. Then add 1/4 cup (~60 g) of the Adobo Sauce (amount as original recipe is written // adjust if altering batch size). Sir to combine and cook for 2-3 minutes more. Then remove from heat and set aside.
Add cooked butternut squash to a mixing bowl along with black beans and 1/4 cup (~60 g) of the Adobo Sauce (amount as original recipe is written // adjust if altering batch size). Stir to combine and set aside.
Warm tortillas in the still-warm oven to 2-3 minutes, or wrap in a damp towel and microwave for 45 seconds to soften.
Divide toppings between warmed tortillas and garnish with additional sauce (you’ll have leftovers*), diced red onion, and fresh cilantro (optional). Tacos are best when fresh - especially mushrooms. Fillings will keep in the refrigerator for 2-3 days, and sauce will keep in the refrigerator up to 1 week or in the freezer for 1 month (see notes for other uses).
*Tomato sauce can be found at nearly every market, and is a blend of tomato purée with spices, such as salt, pepper, and garlic powder. However, if you can’t find it, just sub tomato purée and add more salt, pepper and a bit of garlic powder. *Leftover Adobo Sauce can be stored in the refrigerator up to 1 week or in the freezer for 1 month. It’s excellent as a sauce for tacos, or enchiladas, such as my Panko Baked Avocado Tacos, Spicy Plantain Black Bean Tacos, or Quinoa Taco Meat. *Nutrition information is a rough estimate calculated with all of the sauce and with black beans.