Preheat the oven to 425° F.Place the sweet potatoes on a baking sheet and toss with olive oil, chili powder, paprika, cumin, garlic powder, red pepper flakes, oregano, and salt. Add the poblano and toss to combine. Arrange in an even layer. Bake 35 to 40 minutes, until the potatoes are tender and beginning to char on the edges. Remove from the oven and stir in the black beans.Meanwhile, make the crema. Combine all ingredients in a glass jar and shake or stir until creamy. Line the taco shells up on a sheet pan or in a 9x13 inch baking dish. Transfer to the oven and bake 5 minutes. Evenly divide the sweet potatoes among each taco shell and top with cheese. Bake 10 minutes, until the cheese has melted.Mix the cilantro and jalapeño in a small bowl. Serve the tacos topped with crema, avocado, and the spicy cilantro. Enjoy!