best green bean casserole recipe

1 pound fresh green beans, trimmed and cut into 1-inch pieces (or 2 cans, 14.5 ounces each, green beans, drained) - 1 can (10.5 ounces) cream of mushroom soup - 1/2 cup milk - 1 teaspoon soy sauce - 1/4 teaspoon black pepper - 1 1/3 cups French-fried onions, divided