Step 1

Mix the salt, cayenne, dry mustard and flour together. Dust the hearts with it. Heat the duck fat in a pan over medium-high heat.

Step 2

When it's hot, drop the hearts into the pan and saute them for 3 to 4 minutes, shaking the pan and letting the little hearts roll around a bit.

Step 3

Add the grated onion, Worcestershire sauce and broth into the pan and scrape up any browned bits on the bottom of the pan with a wooden spoon. Swirl everything around so the hearts get coated. Let the sauce reduce to a glaze, about 3 minutes or so over high heat. Mix in the parsley and serve with watecress and crusty bread.