Rinse the basmati rice under cold water until the water runs clear.
In a saucepan, combine the rice, water or vegetable broth, lime zest, lime juice, and half of the chopped cilantro. Bring to a boil, then reduce heat to low. Cover and simmer for 15-20 minutes, or until the rice is tender and the liquid is absorbed.
While the rice cooks, cook the chicken breasts in a pan with a drizzle of olive oil over medium heat until fully cooked (about 5-7 minutes per side). Season with salt and pepper. Let rest, then slice into strips.
In a small bowl, mix minced garlic, the juice of half a lime, and the remaining chopped cilantro to make a tangy lime-cilantro sauce. Set aside.
In another pan, sauté the corn and diced tomatoes briefly until slightly softened. Add black beans and mix through.
To assemble the bowls, spoon the cooked rice into serving bowls. Top with chicken slices, the bean-corn mixture, and avocado slices.
Drizzle the lime-cilantro sauce over the top and garnish with optional extra lime wedges and cilantro.