Bring a large saucepan of salted water to a boil. Add the green beans and cook for 4 minutes, until they are bright green and just tender. Drain and rinse under cold tap water to cool them down. Shake off any excess water and set aside.
Heat a large skillet over medium-high heat and add the olive oil. Add the garlic and crushed red pepper flakes. Stir constantly for about 30 seconds, watch closely to avoid burning.
Add the green beans to the skillet and toss everything together for 2 minutes, until the beans are heated through and coated in the garlic-chili oil.
Season with kosher salt and black pepper, and serve warm.