In a bowl, gently mix ground beef, ground pork, soaked roll, onion, egg, mustard, spices, and parsley. Mix just until combined to keep the meat fluffy.
Shape mixture into patties.
Heat oil in a pan over medium heat. Cook patties for about 15 minutes, turning twice, until fully cooked and golden brown.
Potato Salad:
Boil potatoes with peel on until tender. Let cool slightly, then slice.
Heat beef stock and add diced onions. Pour hot stock over potatoes and let sit at least 30 minutes to absorb flavor.
In a separate bowl, whisk together salt, pepper, sugar, mustard, vinegar, oil, chives, and parsley.
Pour the dressing over the potatoes and gently toss to combine. Adjust seasoning to taste.
Serving and Storage Tips
