A messy sandwich, but it's a treat. Warm Moroccan spices mix with sweet onions to give leftover turkey a fresh spin. Try it with a glass of barely off-dry Gewürztraminer. Prep and Cook Time: 1 hour. Notes: Make the Charmoula Mayonnaise while the onions are caramelizing. You'll have more mayo than you'll need for 4 sandwiches, but the leftovers—which keep for at least a week—are great with roast chicken or beef; broiled salmon; as a dip for poached shrimp, cracked crab, and vegetables; or over poached eggs on English muffins.
Pour olive oil into a large frying pan over medium-high heat. When hot, add onions and cook, stirring often, 5 minutes. Reduce heat to medium-low and cook, stirring occasionally, until onions are golden brown, about 45 minutes total. Season to taste with salt and pepper.
Layer turkey on sandwich roll bottoms and mound with caramelized onions. Drizzle generously with Charmoula Mayonnaise, then add lettuce leaves and roll tops.