Heat oil in large nonstick skillet over medium heat. Add half of bacon slices to skillet; cook for 5 minutes, turning over halfway through cooking. Transfer to plate. Repeat with remaining bacon.
Add onion to skillet; cook 1 minute. Add brewed coffee. Stir together cornstarch and pineapple juice in small bowl until blended. Stir into skillet, along with brown sugar and salt if using. Bring to simmering, stirring until thickened, and cook 2 minutes longer.
Add bacon slices to skillet to warm through. Serve with mashed potatoes and cooked broccoli, if you wish.