For the beef: In a large crockpot, add beef brisket, beef broth, red onion, garlic, cilantro, lime juice, apple cider vinegar, chipotle in adobo and bay leaf. Cook on low heat for 8 hours, or until the beef can easily pull apart and salt to taste.
In a small sauté pan, heat oil on medium to high heat. Add pepper and cook until tender, approximately 8 minutes.
On a medium plate, lay tortilla and evenly distribute cheese. Microwave for approximately 25 seconds, or until cheese is melted.
In a small bowl, slice avocados into cubes and stir in lime juice. Salt to taste.
Add beef and sautéed pepper to the guacamole mixture and gently stir until well combined.
Place guacamole in center of tortilla, on top of melted cheese.
Skewer tortilla and drizzle enchilada sauce on top. Garnish with sour cream and cilantro.