Combine first 12 ingredients in a doubled cheesecloth bag; tie securely with string. Bring 4 to 5 quarts of water to a boil. Add salt, lemon halves, garlic, onion flakes, and herb bag; return to a boil, and cook 2 to 3 minutes. Stir in shrimp; return to a boil, and cook 3 to 5 minutes. Drain well; chill. Peel shrimp. Serve on lettuce leaves and garnish with lemon slices if desired. (would be good served with Seafood Sauce or Seafood Dip.) Yield: 8 to 10 servings. NOTES : Submitted by Dave Shuppert, Dallas, Texas. Recipe by: Southern Living 1979 Annual Recipes Posted to MC-Recipe Digest V1 #836 by NGavlak@aol.com on Oct 10, 1997