Spread pecan halves on a cookie sheet and toast for 5 minutes, stirring once.
While pecans are toasting, butter sides of a 2 quart saucepan. Combine water and next 3 ingredients in saucepan. Heat and stir until sugar dissolves and mixture comes to a boil. Continue to cook while stirring constantly, until the mixture comes to soft ball stage (236 degrees). Remove from heat and beat by hand for 1 minute or until mixture begins to get creamy.
Add vanilla and warm nuts to sugar mixture and spread on a cookie sheet. Acting quickly, use two forks to separate the pecans so that they do not clump together as they cool.