The trick to cooking farro, a variety of wheat cultivated in Italy, is to boil it in lots of salted water, as with pasta.
Slideshow: More Terrific Farro Salads
In a large saucepan of boiling salted water, cook the farro until al dente, about 25 minutes. Drain well. Transfer to a bowl and let cool to room temperature.
In a bowl, mix the olive oil and vinegar and season with salt and pepper. Add the tomatoes, arugula and dressing to the farro and toss well. Season with salt and pepper and serve at once.