Potatoes: Preheat grill to medium heat.
In a large bowl add olive oil, barbeque seasoning, garlic and lemon juice. Mix well to combine. Add potatoes and toss to coat.
Place potatoes in an aluminum foil pouch and seal. Place on the grill or in a preheated 400 degree F oven for 20 to 25 minutes until potatoes are tender.
Sauce: Combine all ingredients in a small bowl. Put the potatoes into a medium bowl and pour in the sauce. Toss well to coat the potatoes or serve the sauce on the side.