Preheat your oven to 425°F (220°C). Line a baking sheet with parchment or foil for easy cleanup.

Place the husked tomatillos, quartered onion, garlic cloves, and whole jalapeños on the baking sheet. Drizzle with olive oil and toss gently to coat.

Roast for 8-10 minutes, until the tomatillos are softened and starting to brown in spots, and the onion edges are charred. The garlic should be fragrant and soft. Let cool for 5 minutes.

Transfer the roasted vegetables to a blender or food processor. Add cilantro, lime juice, salt, and cumin if using. Pulse until you reach your preferred consistency — I like it slightly chunky with visible bits of onion and jalapeño.

Taste and adjust salt or lime juice. If the salsa is too thick, add water 1 tablespoon at a time until it flows like a thick sauce.

Serve warm or at room temperature. For a cooked salsa, transfer to a small saucepan and simmer gently for 5 minutes to meld flavors (optional).