Place the cut potatoes in cold water for 20 minutes. Drain and dry very thoroughly with clean towels.
Heat the oven to 450 F. Toss the potatoes with oil and salt, spread them in a single layer on a sheet pan, and bake for 35 to 40 minutes, turning once, until crisp and golden.
Make the Gravy:
Melt the butter in a saucepan over medium heat. Whisk in the flour and cook for 2 minutes until lightly golden.
Gradually whisk in the warm stock. Simmer for 5 to 7 minutes until smooth and thick enough to coat a spoon.
Stir in the Worcestershire sauce and pepper. Taste and adjust the seasoning.
Assemble:
Divide the hot fries among four bowls and scatter the cheese curds over them.
Pour the hot gravy over the fries and curds. Serve immediately.
Notes
Fresh cheese curds are best because they soften without completely melting.
Keep the gravy hot but do not boil it after thickening.
For extra-crisp fries, use a wire rack over the sheet pan.