How to Make It
Preheat the broiler. On a rimmed baking sheet, toss the tomatillos with the poblanos, serrano, onion, garlic, olive oil and oregano and spread in a layer. Broil 5 inches from the heat for 10 to 15 minutes, or until the vegetables are blackened in spots.
Scrape the vegetables into a blender and puree until nearly smooth. Transfer the salsa to a medium saucepan, season with 1 teaspoon of salt and bring to a simmer. Cook until thickened slightly, about 5 minutes. Let the salsa cool to room temperature. Stir in the cilantro and lime juice, season with salt and pepper and serve.