Cook rice according to package directions using stock instead of water for extra flavor. When done, stir in fresh lime juice and 1/4 cup chopped cilantro. (Consider using a rice maker or instant pot to simplify cooking process and easily keep it warm).
Meanwhile, slice zucchini and squash lengthwise into 4-5 long pieces. Slice bell pepper into about 4 large pieces. Brush veggies with oil and season with salt and pepper. Add chili seasoning if desired.
If grilling up meat, prep that too by brushing with a little oil and then seasoning with chili seasoning, salt, and pepper.
Light grill. While grill is heating up, work on putting out or prepping your desired "additional burrito fillings".
Transfer the rinsed and drained black beans into a small pot on the stove and heat on low.
Grill veggies for 2-3 minutes on each side, until nice grill marks form. Also, grill meat if using. (Chicken breast generally takes 5-7 minutes on each side and should be cooked until no longer pink inside. Fish can take anywhere from 4-7 minutes per side depending on how thick it is; grill fragile fish on foil). Grill steak until desired degree of doneness).
Transfer cooked veggies to clean platters. Let cool a bit and then chop into smaller pieces for adding to the burritos. Heat the tortillas on the turned off but still hot grill (or heat in the microwave if easier).
Assemble the burritos and enjoy!
