Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   6                    garlic cloves -- unpeeled
   1      small         white onion -- sliced
                        -- into 1/4-inch-thick rounds
   6      ounces        ripe tomatoes
     3/4  teaspoon      freshly ground black pepper
     1/8  teaspoon      freshly ground cloves
     1/4  cup           water
   2      tablespoons   olive oil
   2      tablespoons   minced canned chipotle chilies
                        -- (2 to 4)
     1/2  teaspoon      salt
   2      pounds        shrimp -- (medium-large)
                        -- peeled deveined, tails intact

Preparation:

Recipe by: San Diego Union-Tribune To roast the flavorings, cook garlic on an ungreased griddle or in a heavy skillet over medium heat, turning occasionally, until soft, about 15 minutes; they will blacken in spots. Cool and peel. Meanwhile, lay the onion slices on a piece of foil on the griddle; cook until browned and soft, about 5 minutes per side. Roast tomatoes on a baking sheet in the broiler until blackened in spots and soft, about 6 minutes per side. Cool and peel, collecting all the juices. Puree garlic, onion and tomatoes in a blender or food processor with pepper, cloves and water. Heat oil in a large skillet over medium-high heat. When hot, add puree all at once. Cook and stir several minutes until mixture darkens, then reduce heat to medium-low and continue cooking and stirring until mixture is very thick, about 5 minutes. Stir in the chipotles a tablespoon at a time, tasting after each addition, until the level of spiciness suits you. Add salt to taste. Add shrimp, raise heat to medium high and cook, stirring slowly, 3 to 4 minutes or until shrimp are just cooked through. Serve hot or at room temperature. 6 servings. The sauce can be made several days ahead of time and refrigerated. "Rick Bayless's Mexican Kitchen: Capturing the Vibrant Flavors of a World-Class Cuisine" by Rick Bayless (Scribner,).