Classic Green Bean Casserole:

1. Preheat oven to 350°F (175°C).
2. If using fresh green beans, blanch in boiling water for 4–5 minutes until bright green and tender-crisp. Drain well. If canned, drain thoroughly.
3. In a large bowl, mix cream of mushroom soup, milk, soy sauce, and black pepper until smooth.
4. Stir green beans into sauce until evenly coated.
5. Transfer mixture to a greased 9×13-inch casserole dish.
6. Bake uncovered for 25 minutes until hot and bubbling.
7. Remove from oven, sprinkle crispy fried onions evenly over the top.
8. Return to oven and bake an additional 5–7 minutes until onions are golden brown.
9. Serve warm.

Homemade Crispy Onion Topping:

1. Separate onion slices into rings. Toss in flour mixed with salt, pepper, and paprika until coated. Shake off excess flour.
2. Heat about 1 inch vegetable oil in a heavy skillet to 350°F (175°C).
3. Fry onions in batches for 2–3 minutes until golden and crispy. Avoid overcrowding.
4. Remove with slotted spoon and drain on paper towels. Let cool before using.

From-Scratch Creamy Mushroom Sauce (optional replacement for canned soup):

1. Melt butter in skillet over medium heat. Add mushrooms and cook 5–7 minutes until softened and browned.
2. Add garlic and sauté 1 minute.
3. Sprinkle flour over mushrooms, stirring for 1–2 minutes to form a roux.
4. Slowly whisk in milk and vegetable broth, stirring until thickened.
5. Stir in soy sauce, salt, and pepper. Remove from heat.
6. Mix with blanched or canned green beans and proceed with casserole assembly