Use a gallon size Ziploc bag or a large bowl with a lid and add in the chipotle sauce, pineapple juice, achiote paste, onion, garlic paste, lime juice, ground cumin, oregano, and salt. Mix the marinade ingredients around until everything is fully incorporated.

Reserve about ¼ cup of the marinade off to the side. Now add the chicken into the marinade mixture. Toss the chicken around until everything is evenly coated. Place the chicken in the refrigerator and allow it to sit for at least 30 minutes, or overnight for the best flavor.

When you are ready to cook the chicken, heat a large skillet over medium high heat. Pour the olive oil in the skillet. Now gently add the marinated chicken into the skillet in one single layer.

Sear the chicken on each side for about 10 minutes, depending on the thickness of each piece. You want the chicken to form a nice crust on the outside, and reach an internal temperature of 165ºF.

Remove the chicken from the skillet and let it rest on a cutting board for at least five minutes before cutting it into bite size pieces. Once you cut the chicken into pieces, toss it in the reserved al pastor marinade, and enjoy!