Cut your grass fed beef and beef fat into cubes that fit your grinder easily. Keep everything cold, even partially frozen, since warm fat smears instead of grinding cleanly. Run it all through a coarse grinding plate first for the best texture in your final salami.
Add your salt, curing salt, pepper, garlic powder, smoked paprika, and any optional spices to the ground meat. Pour in the wine or broth along with the milk powder or soy protein concentrate. Mix thoroughly by hand or in a stand mixer until the mixture feels tacky and holds together.
If you are using a starter culture, dissolve it in a small amount of cool water first. Fold it into the meat mixture gently so it distributes evenly throughout. This step is what gives traditional salami its tangy, slightly fermented flavor.
Load your seasoned meat mixture into the sausage stuffer and fill your prepared casings snugly. Work slowly to avoid trapping air pockets, which can cause spoilage spots later. Tie off both ends tightly with butcher's twine once each casing is filled.
Hang the stuffed salami in a warm spot, around 70 to 85 degrees Fahrenheit, for 12 to 24 hours. This fermentation step allows the culture to develop that classic tang and helps preserve the meat safely. Keep humidity moderate so the casings do not dry out too fast.
Set your smoker to a low temperature, around 100 to 130 degrees Fahrenheit, and gradually increase it over several hours. Smoke the salami until the internal temperature reaches 152 degrees Fahrenheit, which usually takes 4 to 6 hours. Use a digital thermometer throughout so you never have to guess.
Once smoked, let the salami hang at room temperature until it cools completely, then refrigerate for a few hours before slicing. Slice thinly with a sharp knife or meat slicer for the best texture and presentation. Store any extra in the refrigerator right away to keep it fresh.