Preheat the oven to 350 degrees. Spread the sesame seeds on a baking sheet in a single layer. Bake for 5 to 6 minutes, or until the sesame seeds are crisp and fragrant.
In a large steamer pot, bring 4 cups water to a boil. Add tea bags. Place green beans in the steam rack. Be sure the water doesn't rise onto the rack. Steam at medium-high heat, covered, until beans are bright green, about 4 minutes. Sprinkle raisins into the steam basket and steam for one more minute.
In a large salad bowl, toss green beans and raisins with vinegar, sesame oil, and sesame seeds. Garnish with Parmesan cheese. Serve immediately.