HEAT oil in large skillet over medium-high heat. Add carrots, celery, onion, peanuts, garlic and sesame seeds; cook for about 10 minutes, stirring occasionally, until onions are golden brown. Add vinegar, stir quickly to deglaze skillet. Add chicken stock, chocolate, chiles, cumin and black pepper. Cook, stirring occasionally, until sauce is reduced slightly, about 20 minutes. Remove chile halves; discard. Carefully transfer mixture to blender container; cover. Blend until smooth. Makes about 2 cups. Mole sauce may be refrigerated for up to 7 days or frozen for later use.
HEAT mole sauce in saucepan over medium heat. Additional chicken stock may be needed to dilute sauce to desired consistency. Typically, mole should just coat the back of a spoon. Add shredded chicken. Reduce heat to medium-low; cook until chicken is heated through. Season to taste.
SPRINKLE with sesame seeds. Serve with warm corn tortillas and/or hot cooked rice.