For a spicier sauce there is no need to seed the jalapeno pepper.
- In a shallow dish, combine soy sauce, oil, oregano, cumin, paprika and garlic. Add turkey breast and turn to coat evenly. Cover and refrigerate for at least 3 hours or up to overnight.
- Aji Sauce: Meanwhile, in a blender or food processor, pulse together cilantro, peppers, jalapeno, and shallot. Add mayonnaise and whirl until smooth. Cover and refrigerate.
- Preheat grill to medium heat and add turkey breast. Grill for about 20 minutes, turning twice or until juices run clear and no longer pink inside. Remove to cutting board. Let stand for 5 minutes. Slice thinly and serve with Aji Sauce.