Heat oven to 325°. Spread pecan halves on a parchment paper-lined baking sheet. Bake until lightly toasted and fragrant, about 10 minutes; set aside.
Boil brown sugar, balsamic vinegar, and olive oil in a 12" skillet over medium-high heat. Cook until mixture is foamy and slightly thickened, 2–3 minutes.
Add pecans and cook, stirring constantly, until well coated, about 3 minutes.
Spread on prepared baking sheet and sprinkle with sea salt; let cool completely.
Break into bite-size pieces before serving.
