The night before you intend to cook the beans, sort through beans and discard of any rocks or pebble fragments, rinse and transfer to a large bowl. Cover with water by 2-3 inches and allow to soak overnight.

Preheat the oven to 325°.

Strain the beans, rinse and set aside until ready to use. Have ready a plate lined with paper towels. Place Dutch oven over medium-high heat and the cubes of bacon. Saute for 8-10 minutes, or until the bacon is crispy. Remove bacon with a slotted spoon and set aside on the paper towels to absorb any excess grease. Add the onions and jalapeños and sauté 5-7 minutes, or until softened. Add the rinsed beans, chili powder, salt and pepper, and cover with 4 cups of water. Add the bacon back into the Dutch oven, stir, cover with lid and transfer to the oven.

Bake for 2 hours, covered. Remove lid, add 1 ½ cup of water to the beans, stir and bake for 1 hour more, uncovered, stirring occasionally. Remove from the oven, stir in sliced jalapeño (if desired), serve and enjoy.