Combine the lamb, pork fatback, mint, chipotles, chives, black pepper, orange zest and 2 tablespoons salt in a bowl. Transfer to a large plastic zip-top bag and refrigerate overnight.
At least 30 minutes before grinding the meat, place all of your tools (including the meat grinder parts, stand mixer bowl, stand mixer paddle attachment and sausage stuffer parts) in the freezer to chill.
Using your meat grinder, grind the marinated meat mixture through the small die plate into the chilled bowl of the stand mixer. Refrigerate at least 30 minutes, then return the mixture to the mixer. Add the milk and wine and beat on medium speed using the chilled paddle attachment until combined. Refrigerate until ready to use.
Stuff the sausages and, for best results, refrigerate overnight.
Before cooking, pierce each sausage several times with a pin. Grill over medium heat until the center registers 160 degrees F, 10 to 12 minutes. (You can also pan-fry or broil the sausages.) Slice the sausages lengthwise and serve on a split toasted baguette with crumbled feta and roasted peppers.