Step 1

Place pork, veal, and fatback in a large bowl. Chill in refrigerator for at least 1 hour. Set parts of meat grinder, including large cutting die, in freezer. Set bowl and paddle of stand mixer in freezer.

Step 2

Grind meat and fat mixture through chilled meat grinder fitted with a small cutting die, into a large bowl set in another bowl filled with ice. Add salt, white pepper, ginger, mustard, and nutmeg in with the meat. Using chilled paddle attachment and chilled bowl of a standing mixer, mix at low speed for 1 minute. Add eggs and heavy cream and mix at medium speed until liquid is incorporated and sausage is uniform and sticky, about 1 minute longer.

Step 3

Form a small sausage patty; place rest of sausage mixture in refrigerator. Cook patty in a small frying pan over medium-high heat until cooked through. Taste and adjust seasonings of sausage if necessary.

Step 4

Stuff sausage into hog casings and twist into 6-inch links.

Step 5

Light one chimney full of charcoal. When all the charcoal is lit and covered with gray ash, pour out and arrange the coals on one side of the charcoal grate. Set cooking grate in place, cover grill, and allow to preheat for 5 minutes. Clean and oil grilling grate. Place onion slices in foil tray and pour in beer. Place tray on hot side of grill. Nestle sausage in tray and cook until beer begins to simmer, about 4 minutes. Slide tray over to cool side of grill, cover grill, and continue to cook until sausages register 140 to 145°F on an instant-read thermometer, 10-15 minutes, flipping occasionally during cooking.

Step 6

Uncover grill and remove sausages from liquid and place on hot side of grill. Cook, turning occasionally, until sausages are browned and crisp all over, about 3 minutes total. Place each sausage in a roll and top with onions and desired condiments; serve immediately.