How to Make It
In a large bowl, cover the pasilla and guajillo chiles with the boiling water and let stand until softened, about 20 minutes. Stem and seed the chiles; coarsely chop them. Put the chiles in a blender with the garlic, onion, lime juice, olive oil and 1/2 teaspoon of salt and blend until smooth.
In a large pan, pour the chile marinade over the chicken breasts. Turn to coat completely, and let marinate in the refrigerator for 2 to 4 hours.
Light a grill or preheat the broiler. Grill or broil the yellow pepper and tomato, turning, until the skins are charred all over. Transfer to a bowl, cover with plastic wrap and let steam for 5 minutes. Discard the charred skins, stems and seeds and coarsely chop the pepper and tomato. Transfer to a blender and add the Scotch bonnet chile, vegetable stock and olive oil. Blend until smooth and season with salt.
Remove the chicken from the marinade and season the breasts with salt and pepper. Grill or broil over a medium-hot fire for about 8 minutes per side, or until lightly charred and just cooked through. Transfer to plates and serve with the Scotch bonnet sauce.