Preheat the oven to 325°F. Set a heavy ovenproof pot over medium-high heat, add the oil, bacon and onion and cook until the bacon is almost crisp and onions are golden. Add the garlic and cook for another minute. Add the lentils, water, ketchup, barbecue sauce, maple syrup, cider vinegar, mustard, bay leaf, and some salt and pepper to taste.
Bring to a simmer, then cover and transfer to the oven for 30 minutes, or until the lentils are just tender and have absorbed the liquid. Pluck out the bay leaf before serving. Serves 8 or more.