Prick Bratwurst on all sides with a fork. Place in a large skillet with a cover and add enough boiling water to cover. Cover skillet and simmer 5 minutes. Drain off water. Add 2 tablespoons butter to skillet and brown wurst quickly on all sides. Add bay leaf and enough ale to cover sausages. Cover, bring to a boil, reduce heat and simmer 25 minutes. Remove cover and let ale boil rapidly until it is reduced by almost half. Reduce heat and simmer.

Melt butter in a small skillet and sauté minced onion until golden brown. Blend in flour and sauté slowly until mixture is the color of cocoa. Add to the simmering ale and stir in until smoothly blended and thickened. Season to taste with salt and pepper, and a little lemon and sugar if you like a sweet-sour flavor.