Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
  12      ounces        shrimp -- *
   2      tablespoons   vinegar
   1 1/2  teaspoons     lemon juice
     1/4  teaspoon      salt
     1/8  teaspoon      mustard -- dry
                        pepper -- dash of
     1/4  cup           onion; thinly sliced -- 1 small
   1      clove         garlic -- halved
   3      tablespoons   vegetable oil
   1                    jalapeno pepper; pickled -- **
   2                    avocados -- halved and seeded
     1/2  cup           tomato; chopped -- 1 medium

Preparation:

*Shrimp can be either fresh or frozen and should be shelled. ** Jalapeno Pepper should be rinsed, seeded and cut into strips. Thaw shrimp if frozen. In a bowl combine vinegar, lemon juice, salt, mustard and pepper and set aside. In a medium skillet, cook the shrimp, half of the onion slices and the garlic in hot oil over medium-high heat for 4 to 5 minutes, or just until shrimp are done, stirring occasionally. Remove onion and garlic with a slotted spoon and discard. Add shrimp and the remaining oil to the vinegar mixture in the bowl, along with remaining onion slices and the jalapeno pepper. Cover and chill for several hours or overnight, stirring occasionally. To Serve: Lift the shrimp, onion slices and jalapeno pepper from the marinade and spoon into the avocado halves. Sprinkle with the chopped tomato and drizzle some of the remaining marinade over all.