Heat the oil in a large skillet over medium high heat. Once oil is shimmering, add the onion, garlic, and bell pepper. Season with cumin, chili powder, and salt and pepper. Stir and add the vegetable broth. Cook until vegetables are soft, about 5 minutes. Set aside.

Wipe out the skillet and add a collard leaf, press down with a spatula for 5 seconds, flip, and repeat. Continue with all collard leaves until all are warmed. Then, halve the thickness of the collard stems by slicing horizontally down the stem. Set aside.

Gather all of your filling ingredients. Set out a collard leaf on a clean, flat surface. In the middle of the leaf, spread out 2 tablespoons of guacamole. Top with 2 tablespoons each of the black beans and the bell pepper mixture, and then finish with 2 tablespoons of the brown rice. Fold the ends of the collard leaves inward and start to roll your burrito, packing everything in tightly as you go. Finish seam side down. Repeat until all ingredients are used up. Serve.