Line a rimmed baking sheet with a nonstick baking mat.

Heat sugar and the water to a simmer in a heavy saucepan over medium heat, stirring occasionally, until sugar is dissolved.

Stop stirring; cook until syrup comes to a boil, washing down sides of pan with a wet pastry brush to prevent crystals from forming.

Boil, gently swirling pan occasionally, until mixture is light amber.

Remove from heat.

Stir in pecans with a wooden spoon to coat completely.

Immediately remove pecans from caramel; spread in a single layer on prepared baking sheet.

Let cool completely before using or storing; break into small pieces, if necessary.