- In a saucepan, bring the maple syrup, shallots, and garlic to a boil. Simmer for about 3 minutes. Add the remaining ingredients and bring back to a boil. Simmer for about 5 minutes or until the sauce is syrupy. Set aside. Makes about 500 ml (2 cups).
- In a bowl, combine the chicken with 125 ml (½ cup) of the barbecue sauce and the oil. Allow to marinate in the refrigerator for about 10 minutes.
- Preheat the grill, setting the burners on high. Oil the grate.
- Grill the chicken for 4 to 5 minutes on each side or until cooked. Slice thinly or chop coarsely. Keep warm.
- Toast the buns and spread the inside with mayonnaise. Divide the chicken on the bottom buns and drizzle with barbecue sauce. Layer with avocado and lettuce. Cover with the top buns.
The remaining sauce will keep for at least three weeks in the refrigerator.