Preheat oven to 350 degrees and oil or butter a 2-quart baking dish or souffle dish. Heat a dry skillet over moderate heat and add the sesame seeds. Cook, stirring or shaking the pan, until the seeds begin to smell toasty, about 5 minutes. (They will begin to pop at this point.) Remove from the heat and transfer to a food processor, blender, or mortar. Grind to a coarse meal. Steam the beans for 3 to 5 minutes until crisp-tender. Refresh under cold water. Toss with the minced onion, flour, salt, yogurt and wine. Turn into the prepared baking dish and top with the cheese. Spread the ground sesame seeds over the top and dot with the butter. Bake for 30 minutes, or until the top browns.