Salt and pepper the beef cutlets. Top each roulade with a slice of ham and a sage leaf, roll up and tie tightly. Peel and quarter the onion.
Heat the butter in a pressure cooker and brown the roulades and onions in it all around. Dust with flour, pour in clear soup.
Bring to a boil briefly, then add salt and thyme. Close the lid of the pressure cooker and cook for about 20 minutes.
Remove the thyme. Remove the strings from the roulades before serving.