How to Make It
1. In a small bowl, whisk the mayonnaise with the apple and horseradish. Season with salt and pepper.
2. In a large nonstick skillet, cook the bacon over moderate heat, turning occasionally, until browned and crisp, 5 to 7 minutes. Transfer to paper towels to drain.
3. Wipe out the skillet and heat the oil in it. Season the salmon with salt and pepper and add to the skillet. Cook over moderately high heat, turning once, until just cooked through, 6 to 8 minutes.
4. Spread the apple-horseradish mayonnaise on the buns and top with the salmon, bacon and lettuce. Close the sandwiches and serve.