Add the Parmesan, olive oil, vinegar, oregano, Greek yogurt, shallot and mustard to the bowl of a food processor or blender. Puree until smooth then season to taste with salt and pepper. Cover and refrigerate in an airtight container until ready to use, up to 3 days in advance.
For assembly and serving:
Set the ears of corn over a gas burner on high heat (or on a baking sheet in the oven set to broil on high). Roast until the ears of corn are charred all over, turning occasionally, about 4 minutes total. Remove to a cutting board and cut the kernels off the cob.
Heat oven to broil on high. Lay the slices of prosciutto out on a baking sheet in a single layer. Broil until the prosciutto is golden, about 1 to 2 minutes.
Flip the prosciutto with tongs and continue to broil until crispy, about an additional minute. Be sure to check on the prosciutto frequently so it does not burn.
Remove to a plate and crumble the prosciutto. Set aside until ready to use.
Add the butter lettuce and frisée to a large salad bowl. Add ⅓ cup of the dressing and toss to combine. Add more dressing if desired. Top with the corn, crumbled prosciutto, Parmesan and radish slices. Toss to combine once more and serve immediately.
Video
Notes
Replace the frisée with arugula or endive if you prefer a different flavor balance. Make sure your lettuce and frisée are well-dried after washing so the dressing clings properly.