Step 1: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easy cleanup.
Step 2: Arrange the halved tomatillos, onion wedges, peeled garlic cloves, and whole chilies (jalapeños and serranos) in a single layer on the prepared baking sheet.
Step 3: Drizzle all the vegetables with olive oil, then sprinkle generously with salt and black pepper.
Step 4: Roast in the preheated oven for 20-25 minutes, or until the tomatillos are softened and lightly charred, the onion and garlic are tender, and the chilies are blistered. Keep a close eye to prevent burning.
Step 5: Carefully transfer all the roasted vegetables and chilies from the baking sheet into a blender or food processor.
Step 6: Add the fresh cilantro leaves and fresh lime juice to the blender.
Step 7: Blend until you achieve your desired consistency – smoother for a restaurant-style salsa, or chunkier for a more rustic feel. Add 1-2 tablespoons of water if the salsa is too thick.
Step 8: Taste the salsa and adjust seasoning as needed, adding more salt, lime juice, or even a pinch of sugar to balance the tartness if desired.
Step 9: Serve warm or chilled with tortilla chips, over your favorite Mexican dishes, or as a vibrant topping for savory breakfasts. Store leftovers in an airtight container in the refrigerator for up to 1 week, or freeze for longer storage.