Preheat your oven to 425°F (220°C).

In a baking dish, place the husked tomatillos, quartered onion, and unpeeled garlic cloves in a single layer. Add cleaned jalapeños if desired.

Roast the ingredients for about 15-20 minutes until the tomatillos are tender and slightly charred.

Allow the ingredients to cool for a few minutes, then peel the skin off the roasted garlic.

In a blender, combine the roasted tomatillos, onion, peeled garlic, jalapeños, fresh cilantro leaves, and lime juice. Blend until smooth.

Season the salsa verde with salt and, if desired, a tablespoon of olive oil. Blend briefly.

Transfer the salsa to a serving bowl and enjoy immediately, or refrigerate for at least an hour for flavors to meld.