Whisk the vinegar, oregano, salt, and pepper together in a medium bowl and let sit for 5 minutes to infuse the vinegar.
Vigorously whisk the olive oil into the vinegar in a thin, steady stream until the dressing thickens. Set aside.
Preheat the oven to 350˚F.
Place the prosciutto slices on a parchment paper-lined baking sheet and bake for 15-20 minutes, until the prosciutto is starting to brown and crisp around the edges like bacon.
Slide the prosciutto, still on the parchment paper, onto a wire rack to cool completely.
Break the cooled prosciutto into bite-size chunks with your hands. (While the prosciutto bakes and cools, slice and prep the rest of your salad ingredients.)
Toss the prosciutto, arugula, radicchio, ciabatta, tomatoes, Gorgonzola, and olives together in a large serving bowl.
Whisk the dressing briefly to recombine if separated, then toss a bit at a time with the salad, tasting and adjusting until it's dressed to your liking.
Serve immediately.