01 -
Combine jalapeños, ají amarillo, cilantro, garlic, mayonnaise, sour cream, lime juice, and vinegar in a blender. Blend on high speed until smooth, scraping down sides as needed. With blender running, slowly drizzle in olive oil. Season to taste with salt and pepper. Transfer to a sealed container and refrigerate until serving time. The sauce will thicken as it sits.
02 -
Pat chicken dry with paper towels and place on a cutting board, breast side down. Using sharp kitchen shears, remove backbone by cutting along either side of it. Turn chicken over and lay out flat. Press firmly on breast to flatten. For stability, run a skewer horizontally through the chicken, entering through one thigh, going through both breast halves, and exiting through the other thigh. Tuck wing tips behind back.
03 -
Combine salt, cumin, paprika, pepper, garlic, vinegar, and oil in a small bowl and mix with fingertips until homogeneous. Spread mixture evenly over all surfaces of chicken.
04 -
Light a chimney full of charcoal. When coals are covered with gray ash, pour out and spread evenly over half of coal grate. Alternatively, set half the burners of a gas grill to high heat. Set cooking grate in place, cover grill, and preheat for 5 minutes. Clean and oil the grilling grate.
05 -
Place chicken skin side up on cooler side of grill, with legs facing toward hotter side. Cover grill with vents open and aligned over chicken. Cook until an instant-read thermometer inserted into thickest part of breast registers 43°C (110°F).
06 -
Carefully flip chicken and place skin side down on hotter side of grill, with breasts pointed toward cooler side. Press down firmly with a wide, stiff spatula to ensure good contact between bird and grill grates. Cover and cook until skin is crisp and breast temperature reaches 63-66°C (145-150°F), about 10 minutes longer. If chicken threatens to burn, slide to cooler side of grill and continue cooking until done.
07 -
Transfer chicken to a cutting board and allow to rest for 5 to 10 minutes. Carve and serve with the green sauce.