Cook sausage and onion over medium high heat until meat is done, but not brown. Break up meat with fork if needed.
Stir in minced apple, drain off excess fat, and cool. Combine mustard and next seven ingredients (mustard through salt) in food processor. With motor running, add oil in a slow stream.
Stuff quail with sausage mixture and place in a dish. Cover quail with mustard marinade and allow to marinate for one or two hours.
Place soaked plank on indirect heat of hot grill. Once plank begins to smoke and crackle, place birds on hot plank (careful not to touch birds to one another). Close lid and grill for approx. 15-20 minutes. Birds should be still be a bit pink.
Vidalia Onion and Black-Eyed Pea Salad:
Soak peas in warm water for one hour. Drain. Place black-eyed peas in saucepan and add enough water to cover by one inch. Add potato and 1 ¾ of salt, bring to a boil over high heat, and reduce to a simmer. Cover and simmer about 15 minutes until peas and potato are tender.
In a large frying pan, heat oil over low heat and add onions and cook, stirring until they are translucent. About 7 minutes. Remove from heat and allow to cool. Combine pea mixture with bell pepper, parsley, basil, chives, vinegar, salt and pepper. Toss in arugula just before serving.
