Heat a gas or charcoal grill or a grill pan over medium high heat.
In a small bowl, mix the salt, chile powder, and brown sugar. Sprinkle over both sides of the pineapple slices.
Brush the grill or grill pan with vegetable oil, and grill the pineapple slices on high heat for 1 minute per side. Reduce heat to low and continue cooking until the pineapple has softened and the sugar has caramelized on the edges, 2 to 3 minutes per side.