Place chiles in a small bowl, cover with boiling water and set aside. Heat oil in a large sauté pan. Pat chicken legs dry with a paper towel and dust pieces with salt and pepper. Sear on medium-high heat until browned on both sides, removing pieces to a platter when done. Reduce heat to low.

Add onion and garlic and sauté until soft. Add the cumin, stir, and then add stock and sherry. Combine then stir in miso. Remove from heat.

Drain chiles, cut in half and remove seeds and cores. Chop chiles and add to sauce along with prunes. Stir.

Return chicken and any chicken juices to pan. Try to cover the chicken with sauce. Cover and simmer on low 20 minutes, basting once more, until chicken is thoroughly cooked. Remove meat to a serving dish. Add vinegar to pan, bring to a simmer and stir.

Add salt if needed, and a little water, if sauce has reduced too much. Spoon sauce and prunes over chicken. Scatter cilantro on top and serve.