In a bowl, add the tomatillos, onion, garlic and 1 tablespoon olive oil. Mix to coat the vegetables with the oil.
On a sheet pan lined with parchment paper, spread the vegetables in a single layer. Place the pan in the oven and roast for 30 minutes.Note: The vegetables should be soft and slightly charred -but not burned.
Remove the pan from the oven and allow the vegetables to cool.
Add the cooled vegetables to a blender. Add salt, black pepper and one tablespoon olive oil. Pulse for 30 seconds. Serve room temperature or cold.
