Make the recaudo: Set a comal or griddle over medium-high heat. Once it’s hot, sprinkle with a little water to check whether it is ready; the water should quickly evaporate. Add the tomatoes, onion, bell pepper, celery and whole garlic and grill until the vegetables darken on the outside, about 7 minutes. Using tongs, flip the vegetables and grill another 7 minutes to darken the other side. Transfer the vegetables to a plate and set aside. Turn the heat to medium-low.
In a small bowl, combine the sesame seeds, pumpkin seeds, oregano, cloves, allspice, bay leaves, pasilla chile and stir to mix thoroughly. Transfer the spice mixture to the a pan and toast until it turns fragrant, about 1 minute, making sure to stir it so it doesn’t burn. Transfer the toasted spices to a blender and add the charred vegetables, achiote powder and chicken bouillon. Blend on high speed until smooth, adding the water to keep the mixture moving as needed. Set aside.
In a small bowl, combine the remaining ¼ cup mustard, the mayonnaise, and ¼ teaspoon salt and stir to make an aioli. This will be added to the chopped cabbage, celery, and onion to make a slaw.
About 30 minutes before you are ready to finish cooking, remove the chicken from the fridge and let it come to room temperature. Remove chicken from boiling water. Place the chicken in a large sauce pot, pour the recaudo over the chicken, and continue to simmer.