Bring a large pot of water to a boil and season generously with salt. Add the green beans and blanch until crisp-tender, 2 to 3 minutes. Immediately transfer to an ice bath to stop the cooking, and then remove to a baking sheet lined with paper towels or a cooling rack to drain.
In a large saute pan over medium-high heat, add the canola oil and butter. When the butter is melted, add the garlic and stir until fragrant, 1 to 2 minutes. Add the green beans, soy sauce, sesame seeds, and black pepper and saute until the sauce reduces slightly and thoroughly coats the green beans, being careful not to overcook beans.
Transfer to a serving dish and serve hot.