Mix garlic, onion, and chili powders with paprika and salt. Rub mixture all over pork tenderloin.

Heat 1 tablespoon olive oil over medium-high heat. Add pork and sear until golden brown on all sides, about 2 minutes per side. Wrap tenderloin in aluminum foil.

Preheat an outdoor grill for medium-high heat and lightly oil the grate. Grill the pork in its foil for 20 minutes.

Meanwhile, mix balsamic vinegar, honey, mustard together with the remaining olive oil. Unwrap pork on the grill and liberally brush the glaze on all sides. Continue grilling, brushing on more glaze, until an instant-read thermometer inserted into the center reads 145 degrees F (63 degrees C), about 10 minutes more.

Allow to rest at room temperature for 5 minutes before cutting. Drizzle with any remaining glaze if desired.