Roast the Tomatillos: Preheat your oven to 400°F (200°C).
Place the husked and rinsed tomatillos on a baking sheet and roast for about 20 minutes, or until their skins are lightly browned and blistered.
Let them cool slightly, then finely chop them along with the roasted chiles, making sure to save any juices. 2.
Sauté the Aromatics: While the tomatillos are roasting, heat the oil in a large, deep skillet over medium heat.
Add the diced onions and minced garlic.
Cook, stirring occasionally, for about 10 minutes until they are very soft and lightly browned. 3.
Simmer the Salsa: Add the chopped tomatillos, chiles, their reserved juices, oregano, and vegetable stock to the skillet.
Season with a generous pinch of salt and pepper.
Stir everything together and bring to a low simmer.
Cook for 10 to 15 minutes, stirring occasionally, until the salsa has thickened slightly. 4.
Finish and Serve: Remove the skillet from the heat and stir in the fresh cilantro and lime juice.
Taste the salsa and adjust the seasoning with more salt, pepper, or lime juice as needed.
Serve at room temperature, or cover and refrigerate for up to a week.
Don't skip roasting the chiles!
Roasting poblanos and serranos deepens their flavor and makes them easy to peel. You can do this under the broiler, over a gas flame, or on a grill until the skin is blackened and blistered all over.
