Whisk marinade ingredients together in a non-reactive bowl and set aside.
With a sharp paring knife, remove stem and core of peppers and dry them well with paper towels.
In a small bowl, mix goat cheese with salt and pepper, to taste. Carefully fill each pepper with goat cheese and place in a shallow non-reactive casserole dish or bowl. Cover with marinade and refrigerate overnight before serving. (For an interesting twist, dip in beer batter and fry)
When ready to serve, remove cherry peppers from marinade and set aside. Using a spatula, transfer marinade to a large bowl, add Arugula and sliced onions and toss well to combine. Divide salad between 8 salad plates, top with a piece of proscuitto and garnish with stuffed peppers.
Homemade Goat Cheese:
In a large non-reactive saucepan, combine goat's milk, buttermilk, and rennet. Heat over low heat to 180 degrees. Transfer to a non-reactive bowl and allow to sit overnight, covered, until curd and whey separate. Line a colander with several layers of cheesecloth and ladle curds into colander. Discard whey. Fold cheesecloth over top of curd and allow to drain overnight, refrigerated. Remove from cheesecloth and season to taste with olive oil, salt and pepper.