For the onions, melt butter in a skillet over medium heat. Add onions and soften 6-7 minutes then season with salt. Add beer and stock, bring to a bubble then reduce heat and simmer 20-30 minutes. Stir in parsley and reserve.
Combine ground meats with a liberal amount of salt and white pepper. Add spices and combine. Let stand 30 minutes. Form 6 patties thinner at the center and thicker at edges for even cooking.
Heat a cast-iron skillet over medium-high heat with vegetable oil, 1 turn of the pan. Cook patties 8-10 minutes, turning occasionally.
Serve burgers on lightly toasted rolls topped with lots of onions. Serve with pickles and mustards of choice, and salt and vinegar chips and red cabbage alongside.
For the Red Cabbage:
Heat canola oil in a large pot with a lid over medium-high heat. Add cabbage, onions and bay; season liberally with salt and pepper. Add seeds and juniper (if using), and cook to soften a bit, 10-15 minutes. Add the vinegar, sugar and apples, and reduce heat to medium; cover. Cook for 1 hour, stirring occasionally, until tender. Adjust seasonings and serve.