Prepare the brown rice according to the package instructions. Once cooked, fluff the rice with a fork, then stir in the fresh lime juice and chopped cilantro.

Heat the olive oil in a skillet over medium heat. Add the chopped yellow onion and sauté for about 5 minutes, or until it becomes soft and translucent. Add the drained black beans, water, and taco seasoning to the skillet. Cook for an additional 5 minutes.

Slightly warm the tortillas. Spoon a generous amount of the cilantro-lime rice and seasoned black beans onto each tortilla. Top with salsa and diced avocado.

Wrap each tortilla around the fillings to form burritos. Serve immediately while warm.