Before starting fill a large bowl with about 10 ice cubes and water (leave room to add green beans). In saucepan bring 6 cups water to boil, add some salt to the water. Add fresh green beans. Boil until tender but not overcooked. When tender drain in colander and shock green beans by immediately submerging into ice water. This will prevent overcooking and retain bright green color. Remove after about 30 seconds to 1 minute and drain in colander. In large heavy skillet over medium heat, add olive oil. Add Mushrooms and Garlic and saute. Continue cooking until garlic becomes tan but not brown (be careful not to overcook the garlic as it will become bitter). Mash garlic into oil with a fork. Add green beans, toss until green beans have been coated and are reheated. Just before serving add sesame seeds and toss. Serve immediately.