Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned about 10 minutes. Drain bacon slices on paper towels. Crumble bacon and set aside. Use the remaining bacon oil to cook the steak and chambray Onion.
Combine water, tomatillos, serrano peppers, dice potatoes, and garlic in a small saucepan over medium-high heat; bring to a boil, cover, and simmer for 10 minutes. Remove from heat and allow to cool. Leave the potatoes in the cooking pot and transfer the rest of the content to a blender; blend until smooth and set aside.
In a large skillet over medium-high heat; cook and stir flank steak in the hot skillet until completely browned. Set the meat aside and cook chambray onions until brown in the same skillet.
Pour the tomatillo sauce into a cooking pot and add the rest of the ingredients. Stir in chicken bouillon and reduce heat to medium. Cover the pot and simmer until the meat is tender, 30 minutes to 1 hour.
Meanwhile, heat pinto beans in a saucepan over medium heat until warm; reduce heat to low to keep warm until needed.
Add the bacon and pinto beans into the cooking pot; mix the ingredients well. Garnish each plate with onion, cilantro, black pepper, and a lime wedge.
