For the quail:
- Combine first five ingredients in a food processor and pulse until thoroughly combined. Place quail on a rimmed baking sheet and slather mixture to cover all sides of meat. Cover and refrigerate at least 90 minutes. While quail cures, soak a large handful of hickory wood chips in water.
- Prepare chimney starter full of coals. While coals heat, remove quail from refrigerator, rinse, and pat dry. When coals turn white, pour to one side of the grill and place the grate on top. Toss quail gently with olive oil. Place on grill, skin-side down, over direct heat and cook for 3 minutes.
- When it is time to flip the quail, add the soaked hickory chips to the coals. Return quail to the grill, on side with indirect heat. Cover grill and allow quail to smoke for 10 minutes.
- Transfer quail from grill to a platter. Spoon sweet corn and vidalia onion relish over quail to serve.
For the relish:
- Place onion and ears of corn on a rimmed sheet pan. Drizzle with olive oil and season with salt and pepper.
- Grill over direct heat until tender and slightly charred, about 8 minutes.
- Remove from heat and let cool. Place grilled onion in a bowl and scrape corn from cobs. Finish by gently stirring in bacon-sherry vinaigrette.
For the vinaigrette:
- In a glass bowl, combine shallots, vinegar, mustard, and thyme. Let sit for 30 minutes.
- In a skillet, warm olive oil over medium-high heat and sauté bacon until crispy.
- Remove pan from heat and transfer cooked bacon to a paper towel.
- Slowly whisk oil into shallot mixture until fully incorporated. Season to taste with salt and pepper.
- Stir in parsley and cooked bacon just before serving.