Vegan Enchiladas Stuffed With Garlic Mashed Potatoes

Heat oil in a large skillet over medium-low. Add chiles and cook, turning constantly with tongs, until slightly darkened in color and fragrant, about 3 minutes. (Be careful not to burn chiles or they’ll become bitter.) Transfer chiles to a medium bowl, leaving oil behind in skillet; reserve skillet. Pour 3 cups hot water (6 cups if doubling base recipe) over chiles and weigh down chiles with a smaller bowl to keep submerged. Let soak until softened, about 10 minutes.

Meanwhile, cook onion, garlic, and salt in reserved skillet, stirring occasionally, until browned and slightly softened, 12–15 minutes. Add oregano and cumin and cook, stirring, until fragrant, about 1 minute. Transfer onion mixture to a blender.

Add chiles and 1 cup chile soaking liquid to blender and purée, adding more soaking liquid if needed, until smooth. (If you don’t have a high-powered blender, you may want to pass purée through a fine-mesh sieve.) You should have 2½ cups chile base. If you have less, add more chile soaking liquid and blend again to combine. Do ahead: Chile base can be made 5 days ahead. Let cool; transfer to an airtight container and chill, or freeze up to 3 months.

Preheat oven to 350°. Purée chile base, canned tomatoes, and broth in a blender until smooth. Transfer to a medium saucepan and season with salt and pepper. Partially cover (to avoid splattering) and bring to a simmer over medium heat; cook, stirring occasionally, until enchilada sauce thickens slightly and flavors meld, 18–20 minutes.

Meanwhile, slice ½" from top of garlic, exposing cloves. Set on a square of foil and drizzle with oil; season with salt and pepper. Wrap up foil to encase garlic and bake until very tender, 50–60 minutes. Unwrap, let cool slightly, then squeeze out cloves into a medium bowl.

Place potatoes in a medium pot and pour in cold water to cover by 2"; season generously with salt. Bring to a boil, then reduce heat and simmer until potatoes are fork-tender, 20–25 minutes. Drain potatoes and let cool slightly, then peel. Transfer to bowl with garlic and add nutritional yeast, mushroom powder (if using), cumin, 1 cup almond milk, and remaining ¼ cup oil; season with salt and pepper. Mash with a potato masher or fork, adding up to ¼ cup more almond milk if needed, until smooth and creamy. Set potato filling aside.

Spread ½ cup enchilada sauce in a 13x9" baking dish. Warm tortillas on a dry comal or an oiled griddle until pliable, about 30 seconds per side and set aside. Spoon ¼ cup enchilada sauce into a shallow dish. Dredge a tortilla in sauce on both sides to coat. Fill with ⅓ cup reserved potato filling and roll up tightly. Place enchilada, seam side down, in baking dish. Repeat process with remaining tortillas, using more sauce as needed and packing enchiladas tightly into baking dish. Spoon more sauce over, reserving some for serving. Cover enchiladas with foil and bake until warmed through, 12–15 minutes.

Uncover and top with white onion, avocado, cherry tomatoes, and cilantro. Serve with remaining enchilada sauce alongside. Do ahead: Enchilada sauce can be made 5 days ahead. Let cool; transfer to an airtight container and chill, or freeze up to 3 months. Reheat before using.