Put the ground pork into a large bowl. Add the wine, garlic, pepper, curing salt, pistachios, and truffles, if using. Mix well with your hands. Divide the mixture in half. Form and press each half into a sausage about 8-inches long and 2-inches in diameter. Take care to press the mixture firmly enough to eliminate air bubbles, which would result in unsightly holes in the sausages. Wrap individually in plastic wrap, twisting the ends to enclose the sausages, and then roll each of them in aluminum foil, twisting the ends of the foil. Refrigerate for at least 3 days to cure. (Freeze 1 of the sausages, if desired, and thaw it slowly in the refrigerator before cooking.)
The very important part of poaching these sausages is to do it at a low temperature for a long time. This makes a big difference in the taste and juiciness of the meat. Bring a pot of water to between 150 and 160 degrees F. Lower the wrapped sausages into the pot, and place a heavy lid that is a little smaller than the top of the pot on top of the sausages to weigh them down in the pot and keep them immersed in the water. Cook in the same temperature range, checking the pot occasionally, for about 1 hour, or until the internal temperature of the sausages is close to the same temperature as the water, about 150 degrees F. To keep warm, let the sausages sit in the 150 to 160 degrees F water until serving time.
Note: Morton Tender Quick Curing Salt is a curing agent composed of 99 percent salt, 1/2 percent sodium nitrate, and 1/2 percent sodium nitrite. If you use regular salt the sausages will be fine to eat but will be gray in color rather than the appealing pink color achieved with the curing agent.