I have been doing some research in authentic Mexican cuisine. We all enjoyed this. You can eat it as a soup or put some in corn tortillas to make tacos. It's pretty versatile. I found this recipe here. 

Carne en su Jugo

INGREDIENTS:
6 slices bacon
3 cups water
4 fresh tomatillos, husks removed
3 serrano chile peppers, seeded and chopped
1 clove garlic, peeled
2 pounds flank steak, cut into 1/2-inch squares
1 tsp Caldo de tomate (tomato bouillon)
4 cups of cooked pinto beans
½ onion, chopped
6 tablespoons chopped fresh cilantro
ground black pepper, to taste
1 lime, cut into 6 wedges

HOW TO PREPARE:

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.

Combine water, tomatillos, serrano peppers, 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. Transfer contents to a blender. Add caldo de tomate. Blend until smooth and set aside.

Place a nonstick skillet over medium-high heat; cook and stir flank steak in the hot skillet until completely browned. Pour tomatillo mixture over beef and bring to a boil. Stir in chicken bouillon and reduce heat to medium. Cover the skillet and simmer until 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.

Stir bacon and pinto beans into flank steak mixture; divide mixture between 6 bowls. Garnish each with onion, cilantro, black pepper, and a lime wedge.