Place chicken in the brine, cover, and place in the refrigerator overnight.
Mix up all of the vinaigrette ingredients except the olive oil with a whisk in a bowl. Slowly add in the olive oil, whisking constantly. Cover and store in the refrigerator.
Toast the walnuts and crisp up the prosciutto in a skillet. Set aside.
Remove chicken from the brine and grill it until the internal temperature reaches 165 degrees with a meat thermometer. Slice.
Toss the lettuces together in a large bowl. Add in fruits and veggies and toss once again.
Add vinaigrette and toss again.
Place dressed salad onto plates, top with cheese, toasted walnuts, crispy prosciutto, and grilled chicken.