Prep all ingredients as listed.
Heat olive oil in a large pan over medium-high heat and sear the beef on all sides until browned. Transfer the beef to a slow cooker. Deglaze the pan with a little beef broth or water, scraping up the browned bits, and pour this into the slow cooker. Add paprika, chili powder, chipotle sauce (if using), remaining beef broth, apple cider vinegar, lime juice, onion, garlic, oregano, cumin, bay leaf, salt, and black pepper. Stir well and cook on high for 4 hours or low for 6–8 hours until the beef is tender. Shred the beef using two forks and mix it back into the sauce.
Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, mash the banana until smooth. Add vanilla extract and cinnamon, mixing well. Fold in the oats until evenly coated, then gently mix in the dark chocolate chips. Scoop spoonfuls onto the baking sheet, lightly flatten each cookie, and bake for 12–15 minutes until set and lightly golden. Let cool for 5 minutes.
In a bowl, mash the avocado until smooth. Stir in cilantro, garlic, and lime juice, then season with salt to taste. Refrigerate until ready to serve.
Warm the tortillas in a dry skillet over medium heat for 30–60 seconds per side until soft and pliable. Fill each tortilla with shredded beef and spoon some sauce over the top. Add diced tomato, chopped jalapeño, and shredded cheese as desired.
Serve the tacos with guacamole and chips, banana oatmeal cookies, and lemon sparkling water.