Warm Spinach Salad with Bacon, Chicken and Blue Cheese

apple cider vinegar

Dijon mustard

table salt

black pepper

fresh spinach baby variety

cup(s) uncooked radicchio coarsely chopped

slice(s) uncooked reduced fat bacon cut crosswise into 1/4-inch pieces

Cremini mushrooms sliced (about 3 1/2 cups)

large uncooked red onion(s) thinly sliced

pound(s) cooked skinless boneless chicken breast(s) chopped into bite-size pieces

large Granny Smith apple thinly sliced

cup(s) blue cheese crumbled