Rinse farro well under cold running water. Place in a saucepan,cover with cold water,add a good pinch of salt and bring to the boil. Reduce heat and simmer for about 30 minutes,until farro is tender but still retains a definite bite. Drain and set aside.
Meanwhile,place porcini mushrooms in heatproof bowl and pour over boiling water to cover. Allow to stand for 30 minutes.
Wash silverbeet and cut the leaves from stems. Slice stems thinly. Finely chop leaves and set aside.
Heat butter and oil in medium frypan,add silverbeet stems,garlic and onion and cook for a few minutes until softened.
Wipe mushrooms with clean,damp cloth and slice thickly. Add to pan with silverbeet.
Drain porcini mushrooms,reserving liquid. Add drained mushrooms to pan. Toss to combine and cook until mushrooms are softened. Add silverbeet leaves and cook gently for a few minutes.
Remove from heat. Place in large serving bowl. Add drained farro and combine.
Sprinkle over balsamic vinegar and season well with salt and pepper. Add parmesan cheese and check seasoning. Add extra vinegar or a little reserved mushroom liquid if desired.
Serve warm or at room temperature.