1. Using a sharp paring knife, score ham on one side to prevent curling. Pat dry with paper towels.
2. In a skillet large enough to hold ham flat, warm oil over medium-high heat. Add ham and cook until lightly browned and heated through, 3 to 4 minutes per side.
3. Combine mustard, mayonnaise, chipotle and vinegar in a small bowl. Mix well. Season with salt and pepper. Serve ham warm with sauce on the side.