(NOTE: Before starting the preparation of the Chicken Chile Rellenos, begin cooking 1 3/4 to 2 cups of brown or white rice in a separate pan.)
Wash peppers. In a large sauce pan or pot, fill 3/4 full with water and bring to a rolling boil. Place whole peppers in boiling water and blanche for 3-4 minutes on medium high heat.
Gently remove the peppers from the boiling water using tongs and place in a lightly greased 9" x 13" pan.
Using a serrated, sharp knife, carefully cut a T-shaped slit in each pepper, being careful to cut only the top side of the Poblano pepper.
Use a small spoon to carefully scoop out the seeds in each pepper, being careful to not tear the pepper.
Set peppers aside while cooking chicken mixture.
Wash and pat dry chicken breasts. Cut chicken into 1/4" strips or pieces and cook on medium heat in 3-4 T. olive oil in a large pan or dutch oven.
As the chicken begins to brown, add onions, garlic, bell pepper, tomatoes and seasonings. Stir occasionally to prevent ingredients from sticking to pan. Continue to cook for approximately 15 -20 minutes or until chicken is well browned.
Preheat oven to 425 degrees.
For chicken mixture, reduce heat to medium low and add cilantro, raisins, and walnuts. Cook an additional 5 minutes to incorporate the last 3 ingredients into the chicken mixture.
Remove chicken mixture from heat. Use a small spoon to gently fill each Poblano pepper with the chicken mixture--being careful not to tear the peppers.
Place stuffed Poblano peppers in oven and bake for 5-10 minutes.
Remove peppers gently from pan placing onto a bed of (cooked) white or brown rice. (For presentation sake, I prefer to place the rice and one stuffed pepper on each person's plate prior to them being seated at the table.)