Preheat oven to 425F.

Peel and wash tomatillos, slice onion into large quarters, slice jalapenos down the middle to form four total halves. Wrap whole garlic cloves in parchment paper with black pepper and 1/4 tsp oil to form a small roasting pouch.

Lay vegetables on a large baking sheet and cover with salt, white pepper, and remaining oil. Add garlic roasting pouch seam-side down to ensure it does not open while roasting. Roast for 10-15 minutes, or until vegetables have begun to brown.

Combine roasted vegetables, avocado, cilantro, lime juice, lime zest, and cumin to a food processor and blend until smooth. Add additional salt to taste if necessary.