Preheat your oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish.
In a large mixing bowl, whisk together the condensed cream of mushroom soup, milk, soy sauce, and black pepper until the mixture is smooth and fully combined.
Add the trimmed green beans and 2/3 cup of the French-fried onions to the soup mixture, then stir gently until the green beans are evenly coated.
Pour the green bean mixture into the prepared baking dish and spread it into an even layer.
Bake, uncovered, for 25 minutes until the sauce is bubbly and the green beans are tender-crisp.
Remove the dish from the oven and sprinkle the remaining 2/3 cup of French-fried onions evenly over the top.
Return the dish to the oven and bake for 5 more minutes, or until the onions on top are golden brown and crispy.
