Cut the onions into rings. Heat the butter in a pan. Sauté the onion rings for approx. 5 mins., add the paprika and cook briefly, set aside.
Put the frankfurters on a griddle pan and cook on all sides for approx. 6 mins., remove from the pan. Cut the baguettes in half and cut open lengthwise. Place the bread on the hot griddle pan, cut side down, and grill for approx. 6 mins.
Combine the mustard and honey, spread half inside the baguettes. Insert the frankfurters. Spread the rest of the honey & mustard mixture over the top along with the onions.