Place the beans in a large bowl and cover by one inch with water. Let sit overnight. Drain and rinse the beans, then drain again.
In a large pot, combine the beans with 2 quarts of water, the sliced onion, bay leaf and peppercorns. Bring to a boil, then lower the heat to keep at just a bare simmer. Simmer until tender, about 90 minutes. Drain the beans, making sure to save the cooking liquid.
Preheat the oven to 225°F and arrange an oven rack in the middle position.
In a small saucepan, whisk to combine the maple syrup, brown sugar, ketchup, chili-garlic sauce, ginger, salt and 1 1/2 cups of the cooking liquid (making sure to still reserve the rest of the cooking liquid). Bring to a simmer over medium heat. Simmer for 5-6 minutes.
Transfer the beans to a medium Dutch oven (or if necessary, a large saucepot). Discard the bay leaf. Add half of the sliced bacon and stir gently to combine. Arrange the rest of the sliced bacon evenly over the top of the beans. Pour the maple syrup sauce over the beans. Cover the pot with the lid and bake for 6 to 8 hours. Lift the lid to check occasionally. If the beans look too dry, add 1/2 cup cooking liquid at a time. Remove the lid for the last 30 minutes of cooking to thicken the sauce. Serve hot. Can be kept refrigerated in an air-tight container for up to five days.
