In a large skillet, heat butter and olive oil over medium heat. When skillet is hot, place sliced pork loin into skillet; cook until browned, turning once. After both sides have browned nicely, add chicken stock ,and cook until liquid thickens.
Stir in dry white wine, scraping the bottom of the pan. Reduce heat, and simmer until liquid is reduced by half. Remove from heat, and allow to cool slightly. Stir in cilantro. Spoon sauce over pork when serving.