In a bowl, combine all of the ingredients. Refrigerate until ready to serve.
In a bowl, combine the mashed potatoes, ham, cheese, egg, green onion and ¼ cup (20 g) of the breadcrumbs. Season generously with pepper. Set the remaining breadcrumbs aside in a shallow bowl.
Form the mashed potato mixture into 10 patties using about 1/3 cup (75 ml) for each one. Press the patties into the breadcrumbs to coat on both sides.
In a large non-stick skillet over medium-high heat, brown half of the patties at a time in the butter and oil for 3 minutes on each side or until heated through and nicely browned. Serve the croquettes with the sauce and a vegetable of your choice.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.