BBQ Onion Steaks with Honey-Mustard Sauce

Everything this month is inspired from Bon Appetite, but as always, I have to add a few tweaks.

The original recipe calls for fresh savory, and does not have the marinating step. Anyway this is the formula everyone agrees is the best.

1/4 cup olive oil
2 tablespoons (1/4 stick) butter, melted
1/4 cup Dijon mustard
1/4 cup honey
1 1/2 teaspoons Worcestershire sauce
2 large sweet onions (such as Walla Walla, Vidalia, or Maui), peeled, cut horizontally into 1/2-inch-thick slices.

Run 2 soaked bamboo skewers parallel through each onion slice, placing skewers about 1 1/2 inches apart to keep slice intact. Trim ends of bamboo skewers.
Please onions in a large zip-lock bag and add about a 1/4 cup of olive oil, put in the fridge for about 4 hours, turning to coat every hour.
Prepare barbecue (medium-high heat). Whisk oil and butter in small bowl. Whisk mustard and next 2 ingredients in another small bowl.Brush both sides of onion slices with oil mixture. Place onions on grill and cook until beginning to char, turning and brushing often with oil mixture, about 11 minutes. Brush top side of onions with mustard mixture and cook until mixture begins to bubble, about 2 minutes. Turn onions; brush with mustard mixture and grill until beginning to caramelize, about 1 minute longer. Transfer onions to plate. Brush with mustard mixture.