Cut the beans into 2-inch pieces. Bring a large saucepan 3/4 full of water to a boil. Add the beans and cook until they turn bright green and are tender-crisp, 1 to 3 minutes. Drain the beans, then plunge them into a bowl of ice water to stop the cooking. Drain again and set aside.
In a large frying pan, heat the olive oil over medium heat. Add the bell pepper and toss and stir for about 1 minute. Add the beans and saute for 1 minute longer. Add the chili paste and garlic and stir for 1 minute. The beans will be tender and bright green. Drizzle with the sesame oil and season with the salt and pepper. Serve immediately.