Combine the farro, broth, and 1 cup of apple cider in a medium saucepan. Bring to a boil, then reduce to a simmer. Cook approximately 25 to 30 minutes, or until tender. The majority of the liquid will be absorbed, but there may be a little remaining. Remove from heat and set aside.
Heat 1 tablespoon of olive oil over medium-high heat in a large frying pan or skillet. Add the sliced sausages. Crisp on each side, for approximately 2 to 3 minutes on each side. Transfer the sausage to a plate and set aside.
Add the onion, mushrooms, apple, salt and pepper to the same skillet. Cook over medium-high heat for about 4 to 5 minutes, or until apples begin to soften and mushrooms release their liquid.
Add the remaining 2 tablespoons of apple cider and vinegar to the skillet. Cook about 30 seconds, or until the vinegar evaporates. Reduce heat to medium-low heat. Add the cooked farro and any leftover liquid in the pot. Add the sausage to the pan. Cook approximately 1 to 2 minutes, until warmed through.
Divide the farro among plates and top with walnuts. Enjoy!