Add the aji amarillo, aji panca, lemon zest and juice, soy sauce, beef tallow, paprika, cumin, oregano, garlic, salt, and pepper to a blender. Blend until smooth.
Coat the turkey thighs evenly with the marinade and marinate at least 30 minutes, or overnight.
Preheat a grill or oven to 375F. Grill over indirect heat, or set the turkey on a rack over a baking sheet.
Cook until the thickest part of the thighs reaches 175 to 185F, about 45 to 60 minutes.
For crispier skin, finish over direct heat or raise the oven temperature for the last few minutes, watching closely so the marinade doesn't burn.
Rest 10 to 15 minutes before serving.
Make the green sauce: blend the jalapenos, cilantro, garlic, Greek yogurt, olive oil, salt, and pepper until smooth. Chill and serve alongside.