Mix the roasted pepper with the vinegar in a small bowl. Set aside to soak 30 minutes. Place the grated Cheddar in a large bowl and add the shredded ham, roasted pepper mixture, mayonnaise, paprika, cayenne and 5 or 6 turns of freshly ground black pepper, stirring until well-mixed and creamy. Taste the pimento cheese and season carefully with salt and more cayenne if needed. Cover and store in the refrigerator until ready to use. Pimento cheese tastes best when removed from the refrigerator 15 to 20 minutes before serving.