Spread pecans in a single layer in a baking pan. Bake in a 350° oven until golden under skins, 8 to 10 minutes.
In a 10- to 12-inch frying pan over high heat, combine sugar, lime juice, ground chile, cayenne, and salt. Stir until sugar is melted, 2 to 3 minutes, then stir occasionally until mixture is very bubbly and slightly darker, 2 to 3 minutes longer.
Add pecans and stir until well coated with sugar mixture. Spread in baking pan and let stand until cool to touch, 15 minutes.