To find many difficult to get ahold of and troublesome recipes for cooking, (ex: Crocolisk Steak, Tiger Steak), you seek the Master Cooking Vendor.
Alliance Only:
Kendor Kabonka He's upstairs in the Pig and Whistle Tavern, in Old City in SW. If you're having trouble finding the place, ask a guard to find the Cooking Trainer. Same building, cept he's upstairs and the cooking trainer is down in the kitchen.
Neutral Vendor: In Desolace,[url=
http://thottbot.com/c11626]Rigger Gizelton's Robot, [/url]
the Super Seller 680 carries many of the similar recipes to MCV up in SW. Look here to his robot, and caravan. They walk in a circle pattern as show on Rigger's map, and if someone's on the escort quest you can't access the robot.
Neutral Vendor:
Kelsey Yance in Booty Bay's Port Authority. He doesn't carry as many as The Master Recipe Vendor, but he does have great fish-cooking recipes. Please note he also has a Tailoring pattern in limited supply!
Neutral Fishing Vendor:
Gikkix Many other great fish-cooking recipes found here, Steamwheedle Port, Tanaris.
Outlands: The Rokk in Lower City, Shattrath, does Daily Cooking quests for Level 70's. When you recieve your daily reward, they contain cooking recipes on occassion!
Various Factions have specific cooking recipes. Sporegaar (Pet food for Hunters!), Kurenai, etc. You must have attained reputation with these factions to gain the recipes.
Additionally, if you are looking to find Fish cooking recipes, you can find them off Fishing Suppliers most often, very near Fishing Trainers, generally.