Grilled Radish, Corn and Onion Salad

1 bunch radishes, stemmed and rinsed, cut in half

1 small red onion, peeled and cut into wedges

1 ear corn, shucked 

1 head butter lettuce, washed and torn

1/4 cup mayonnaise

1/4 cup buttermilk

1 tablespoon whole grain mustard

1/2 cup shredded Parmesan 

Salt and pepper

Olive oil

Heat grill or grill pan to medium-high. 

Toss onions and radishes with oil and season with salt and pepper. Coat corn lightly with oil and season with salt and pepper. Grill until lightly charred, then set aside until cool enough to handle. In a bowl, whisk together mayonnaise, buttermilk, and mustard. Stir in Parmesan and season with salt and pepper. Add lettuce and toss to coat. Cut kernels from corn, break onions up and cut radishes into quarters, then add to bowl. Toss again and serve.