Preheat oven to 450 degrees, and line a baking sheet with parchment paper.
Place tomatillos in a bowl of water to soak, then remove husks.
In a large bowl, add tomatillos, onion, garlic, pepper, vegetable oil, cinnamon and cumin. Toss well to coat. Transfer to the prepared sheet tray and roast for 30 minutes, or until golden. Remove from oven and let cool.
Transfer to a blender, then add the cilantro, lime juice and olive oil. Process until smooth. Taste for seasoning and serve.