In a small bowl, stir together mayonnaise, Dijon mustard, lemon juice, and garlic powder. Season with kosher salt and freshly ground black pepper to taste. Mix well until smooth and creamy.
Place one tortilla flat on a clean cutting board or work surface.
Spread a generous amount of the mayo aioli evenly over the center of the tortilla, leaving a 1-inch border all around.
Layer two romaine lettuce leaves over the aioli.
Add half of the turkey breast slices on top of the lettuce, folding them gently for texture and height.
Arrange half of the tomato slices evenly across the turkey.
Top with half of the sliced red onion.
Fold the sides of the tortilla inward, then roll it up tightly from the bottom like a burrito.
Repeat with the second tortilla and remaining ingredients.
Slice each wrap in half on a diagonal and serve immediately. You can secure them with toothpicks if needed.