Cook the beans in a large pot of boiling water (salted), for approximately 3 minutes. Once cooked drain the beans and place in a bowl of ice water to cool, and then drain.
In a small bowl whisk together the miso paste and butter.
In a large frying pan, heat the canola oil over medium-high heat. Add the beans, season with salt and pepper. Add the garlic and the shallow and cook for 1 minute. Add the vegetable broth and cook until the sauce begins to thicken and reduces by half of the original quantity, around 1 minute.
Lower you heat, and add the miso butter; stir until the sauce becomes slightly creamy. Serve Immediately