Heat vegetable oil in sauté pan over high heat. Add butter to pan and brown slightly. Add onions to pan and sear for about 1-2 minutes.
Add brown sugar and salt. Stir well and continue cooking for approximately 10 minutes, or until onions are light brown, stirring constantly to prevent burning.
When onions began to caramelize, add bourbon. Continue cooking until all liquid is cooked off and onions are a nice brown color.