Stuffed Poblanos & Filling:
Rajas Sauce:
Stuffed Poblanos & Filling:
Under the broiler on a foil-lined pan, roast poblano peppers, onion, garlic and fresh tomatoes (if using fresh) until skins on the peppers are bubbly and charred in places, onion skin is charred and garlic is softened. The fresh tomatoes, if using, should be slightly browned and softened. Turn often, as necessary, and remove each piece to a bowl covered with a kitchen towel as it is finished. When all are finished, allow to steam for several minutes in the bowl.
Remove the skins from the peppers, and when cool, cut a slit from the stem end to the bottom and remove seeds. Set the six best aside and use the other in the rajas sauce, below.
Remove the skins from the onion, squeeze or open garlic to remove pulp, and deseed tomatoes if using fresh.
Place tomatoes (fresh or canned) in the food processor along with garlic, onion and chipotle peppers. If there are juices on the broiler pan or in the bowl the vegetables were steamed in, add them as well. Pulse until nearly smooth.
In the meantime, cook chicken breasts in simmering water until done. Remove, reserving about 1/2 cup of the liquid, and shred the chicken. Discard or reserve the rest of the broth for another use.
Place chicken back in pan and add the pureed tomato mixture. Add 1 teaspoon salt, 3/4 teaspoon cumin, a few grinds of pepper, and the reserved 1/2 cup chicken broth. Cook gently, stirring now and then, until the chicken is nearly dry. Add the teaspoon vinegar. Taste for seasoning.
Keep warm while making the Rajas Sauce, below, then gently heat the peppers in the microwave for a minute until hot, stuff with the warm filling, and top with Rajas Sauce. Serve immediately with lime to squeeze over the stuffed peppers at the table.
Rajas Sauce:
Heat a large dry heavy skillet over medium-high heat. Add onion; cook, stirring often, until beginning to char, 6–7 minutes. Add garlic; cook until fragrant, about 1 minute.
Add chiles and cream and bring to a simmer. Simmer several minutes, stirring often, until the cream is slightly reduced, the onions and peppers softened.
Remove from heat and add in cheese. Stir well. If the mixture becomes too thick (it should be a sauce like consistency and will thicken a bit upon standing or as it cools) it may be thinned with water or additional cream, a tablespoon at a time. Taste and adjust seasoning.