Begin by boiling 3 cups (700 ml) of water in a large pan. Take off the heat, add the cleaned chilies and allow the peppers to soften until the water reaches room temperature. Make sure you remove the seeds from the chilies beforehand to make processing the marinade easier.
Once soft, blend the chillies together with 3 cloves of garlic , oregano, cumin, thyme, cloves, bell peppers and bay leaves, adding about 2 cups (470 ml) of the water the chillies soaked in.
Coat the chicken pieces in the chili pepper mixture and leave to marinate for at least 1 hour, but preferably overnight for the best results.
Next, roll out a sheet of aluminum foil and arrange the cactus paddles and the julienned onions on top. Season to taste. (Tip: If you'd rather use mixiotes sheet, you will need to hydrate it for 10 minutes before using them to prepare the mixiotes)
Add chicken on top and add more marinade and salt if you prefer.
Wrap the mixiotes by folding 2 opposing sides toward the middle and the then remaining two. If you're using mixiote sheet instead, place all the ingredients in the middle, form a sachet by lifting the sides and tie them off using some cotton thread. Make sure the fold faces upwards to avoid the juices spilling.
Steam the chicken mixiotes for 1 hour over low heat.
Serve in a deep dish, open the mixiote carefully and enjoy!