1/4teaspooncayenne pepper , or a splash or two of Chipotle Tabasco
Soak cedar plank in water for an hour or so. While the planks soak, prep the chicken and make the sauce.
Remove skin from chicken thighs. Arrange chicken on a rimmed baking sheet and sprinkle both sides of chicken pieces with onion powder, granulated garlic, paprika, salt and pepper. Set aside.
FOR THE SAUCE
Process onion and water in food processor until pureed. Pass mixture through fine-mesh strainer into liquid measuring cup, pressing on solids; this should produce approximately 3/4 cup strained onion juice. Discard solids.
Whisk onion puree, ketchup, apple cider, sugar, Worcestershire, mustard, molasses, pepper, cider vinegar, and liquid smoke together in medium bowl. Heat oil in nonreactive saucepan over medium heat until shimmering; add garlic, chili powder, and cayenne and cook until fragrant, about 30 seconds.
Stir in ketchup mixture; increase heat to medium-high, bring to boil, reduce heat to medium-low, and simmer, uncovered, until flavors meld and sauce is slightly thickened, about 15 minutes. This will yield about 4 cups of sauce (refrigerate any leftover).
GRILLING THE CHICKEN
On a gas grill, place soaked cedar plank directly over medium heat and allow wood to get hot, 5 minutes. Place chicken directly on the cedar plank and cook over medium-low heat 30-40 minutes (this will depend on the grill, so you may have to adjust the temp to be sure the plank stays hot enough).
As chicken cooks, rotate one or two pieces at a time and cook directly on the grill for a few minutes, then back to the plank. This will help the chicken cook a little faster and create a subtle grilled flavor with the smoke. During the cooking process, the wood plank will char and smoke which is what you want. If the wood should begin to catch fire, simply spray those parts with a little water.
Once the chicken is cooked through, transfer to a rimmed baking sheet and allow to cool until easy to handle.
Remove chicken from the bone discarding any gristle, fat, or connective tissue so that only the meat remains (save the bones for stock). Pull chicken meat apart so that it is in small bite-size pieces.
COMBINE AND SERVE
At this point the chicken and sauce can be refrigerated and then combined just before serving.To serve, toss chicken with desired amount of sauce in a large skillet or oven dish--add as little or as much sauce as you prefer. Heat chicken with sauce in the skillet over medium-low heat or in the oven at 350° until incorporated and heated through. Serve on whole wheat buns and for a special treat, top with coleslaw too!