1. Confit one head of garlic by combining 1?3 cup olive oil and 2?3 cup vegetable oil in a medium saucepan. Add peeled garlic and bring to a simmer; cook for 30 minutes or until garlic is tender.
2. Meanwhile, over an open flame, roast 12 washed and hulled tomatillos and four chilaca chiles.* Once blackened and fragrant, place the chiles in a bowl and cover with plastic wrap. Allow to steam for 5 minutes. Peel.
*Poblanos or Hatch chiles can be substituted.
3. In a blender, combine the garlic, roasted peppers,1?3 cup lime juice, and salt and pepper. Buzz until smooth. Taste and season with additional salt, pepper, or lime juice if necessary.
—Inset illustrations by Peter James Field