In a large gallon size zip-top bag, combine the ingredients for the chicken and toss to combine. Seal and chill at least 1 hour or up to 12 hours.
Meanwhile, cook the farro according to package directions and then add the cooked farro to a large bowl. Add the cherry tomatoes, olives, pepperoncini, cannelini beans, artichokes and mozzarella. Gently toss to combine. Add a spoonful or two of the roasted red pepper sauce and toss.
Set your grill, grill pan or skillet to medium-high heat.
Grill the chicken until lightly charred and cooked through, turning occasionally throughout cooking, about 10 to 12 minutes total. Transfer to a cutting board and allow to rest 5 minutes, then slice into thin strips against the grain. Add the chicken to the farro and serve with the remaining roasted red pepper sauce (see below). Garnish the salad with a large handful of arugula. Serve.