Mix the spice rub. In a small bowl, combine chili powder, cumin, smoked paprika, oregano, salt, and pepper.
This blend is your flavor foundation.
Prep the steak. Pat the beef dry and rub it all over with the spice mix. If the piece is very thick, cut it into 2–3 large chunks for even cooking.
Optional sear for extra flavor. Heat oil in a skillet over medium-high and sear the beef 1–2 minutes per side until browned. This step adds depth but isn’t mandatory.
Layer the slow cooker. Add onions, bell peppers, garlic, diced tomatoes, green chiles, broth, and tomato paste (if using) to the slow cooker.
Stir to combine. Nestle the steak on top and spoon some sauce over it.
Cook low and slow. Cover and cook on Low for 7–8 hours or High for 3.5–4.5 hours, until the steak is fork-tender and shreds easily.
Shred and finish. Transfer the steak to a cutting board and shred with two forks. Stir lime juice and chipotle (if using) into the sauce.
Return the shredded meat to the pot along with the beans. Let it warm through for 10–15 minutes.
Cook your base. While the steak finishes, cook rice according to package directions. For cilantro-lime rice, stir in chopped cilantro, lime zest, and a pinch of salt at the end.
Assemble the bowls. Spoon rice into bowls, top with the steak and plenty of saucy peppers and onions.
Add corn, lettuce, avocado, salsa, cheese, sour cream, cilantro, and a squeeze of lime.
Adjust to taste. Finish with extra salt, hot sauce, or more lime if needed. Serve warm.