In a saucepan, melt the butter over medium heat. Add the chopped onion and cook until soft and translucent, about 5-7 minutes.
Sprinkle in the flour and whisk to combine, cooking for 1-2 minutes to create a roux.
Gradually pour in the beef broth, whisking constantly to avoid lumps. Bring to a simmer and stir in the Worcestershire sauce. Continue to simmer for about 10 minutes, until the gravy has thickened to your liking. Season with salt and pepper to taste. Keep the gravy warm.
While the gravy is simmering, heat the oil in a deep fryer or a large pot to about 180°C (350°F).
Fry the potato fries in batches until they are golden brown and crispy. Remove them with a slotted spoon and drain on paper towels. Season immediately with salt.
Divide the hot, crispy fries among individual serving bowls.
Generously scatter the fresh cheese curds over the fries.
Pour the hot gravy over the curds and fries, ensuring the curds melt slightly. Serve immediately while the fries are still crispy and the gravy is hot.