Prepare the chipotle mayo in advance and store it in a container for up to three weeks. If adobo sauce is unavailable, toast a ripe jalapeno and mix it with 1 tablespoon of tomato paste, 1 tablespoon of apple cider vinegar, 1/2 teaspoon of chipotle powder, and a pinch of oregano, garlic powder, and salt. Keep all the components separately in the refrigerator for 3-4 days and assemble your sandwich fresh. You can also freeze the shredded chicken for up to three months; defrost it in the fridge overnight before reheating.