Prepare a charcoal fire or preheat a gas grill.
Season the skirt steak with salt and pepper and lightly brush both sides with sauce. Cook the steak on the grill for about 3 minutes on each side. Slice the steak diagonally and serve.
Melt the butter in a large heavy-bottomed pot or Dutch oven over medium heat. Add the onion and cook for 5 minutes. Add the garlic and cook for an additional 5 minutes. Stir in the lemon zest, lemon juice, ketchup, tomato juice, brown sugar, molasses, Worcestershire sauce, chili powder, vinegar, chipotle puree, salt and 3 cups water and bring to a boil. Lower the heat and simmer for 30 minutes, stirring frequently.