While you're gathering ingredients, combine the chili powder, smoked paprika, cumin, garlic powder, and onion powder in a small bowl—this ensures even distribution of flavors throughout the meat. Simultaneously, dice the white onions finely, slice the avocados, cut the limes into wedges, and chop the fresh cilantro. Pour the ranch dressing into a serving bowl and refrigerate. Having all toppings prepped means you can serve immediately when the beef is ready, keeping everything fresh and organized.

Place the beef chuck roast directly into your crockpot, then pour the beef broth around it. Add the diced green chilies, brown gravy mix, and the spice blend from Step 1, stirring gently to distribute the seasonings evenly. Scatter the cubed butter over the top—the fat will help carry flavors and create a richly textured sauce. Cover and set the crockpot to low heat for 8 hours. I find that the long, slow cooking breaks down the connective tissue in the chuck roast perfectly, making it incredibly tender and easy to shred.

After 8 hours, carefully remove the beef from the crockpot and place it on a cutting board or in a shallow pan. Using two forks, shred the meat into bite-sized pieces by pulling the forks in opposite directions—the meat should fall apart easily. Return all the shredded beef to the crockpot and stir it thoroughly with the cooking liquid to combine all the flavors and coat each piece. Stir in the fresh lime juice to brighten the sauce and add a subtle complexity. I always taste at this point and add a pinch of salt if needed—the gravy mix and butter already provide richness, so you're just balancing the flavors.

Warm your corn or flour tortillas in a dry skillet over medium heat, about 30 seconds per side, or wrap them in a damp paper towel and microwave for 1-2 minutes until they're pliable and warm. This step prevents them from cracking and makes them easier to fill. Arrange the warm tortillas on a platter alongside the shredded beef in the crockpot (which can be kept on warm setting to maintain temperature).

Let guests build their own tacos by placing shredded beef from Step 3 into a warm tortilla, then topping with diced white onions, avocado slices, fresh cilantro, a drizzle of ranch dressing, and a squeeze of lime wedge. This interactive approach lets everyone customize their tacos to their taste preferences while keeping the components hot and fresh.