Combine all the ingredients in a large stock pot and cover with water by 2 inches.
Bring to a boil over medium-high heat, then reduce the heat so the liquid is barely simmering. Cook until the chicken is tender and cooked through, about 1 hour.
Remove chicken from the pot and set aside to cool.
Strain the liquid through a fine mesh strainer into another large heat-proof container. Discard the solids and save the stock. Let stock cool then cover and refrigerate for up to a week or freeze for up to three months. If you are freezing, don’t forget to save 1/2 cup for the tacos.
Once chicken is cool enough to handle, remove all the skin and bones and shred chicken into large strips.
For the Pico de Gallo:
Combine all the ingredients in a medium bowl and taste. Add more lime juice or salt as needed.
For the Tacos:
Heat the oil in a large frying pan over medium heat add the onion and season with salt and pepper. Cook, stirring occasionally until starting to brown, about 3 minutes.
Add chipotles, the reserved chicken stock, and chicken. Cook until well combined and chicken is heated through, about 3 minutes more. Stir in lime juice and season with salt.
Serve immediately with warm corn tortillas and the mango pico de gallo.