Preheat oven to 425F.
In a large mixing bowl combine the olive oil, sweet potato puree, turmeric, half of the grated garlic, taco seasoning, salt, zest of the lemon, and 1 1/2 cups of water. Stir well.
Ladle a cup of the sweet potato mixture into the bottom of an 8 x 12-inch (or larger) baking dish, or equivalent. Lay the tortillas on a work surface, and divide the black beans equally between them, sprinkle equally with olives. Roll up tortillas, and place seam side down in baking dish. Pour the remaining sauce on top (it will thicken).
Bake the enchiladas for 30-35 minutes, or so. Half way through, sprinkle with sliced almonds, and finish baking - until golden and bubbling. While the enchiladas are baking, thin the tahini with 1/4 cup warm water. Whisk in the remaining garlic, a pinch of salt, and squeeze of lemon juice. Top the enchiladas with dollops of the tahini sauce, and the fresh cilantro when they come out of the oven. Serve hot!
*Serrano Chile Vinegar & Chiles: Combine 8 serrano chiles, sliced 1/8th-inch thick with 2 cups white vinegar in a Mason jar, and refrigerate. Use the chiles w/in a week or two. You can use the vinegar for weeks after that in dressings, etc.