Place the rice in a fine-mesh sieve and rinse under cold water until it runs clear, 30 to 60 seconds.
Cook the Rice
Bring the water or broth, butter, and salt to a boil. Add the rinsed rice, stir once, reduce heat to low, cover immediately, and simmer for 18 to 20 minutes until all liquid is absorbed.
Season the Rice
Remove from heat. Let steam with the lid on for 5 minutes. Add the lime juice, lime zest, and cilantro. Fluff with a fork and fold to distribute. Cover to keep warm.
Warm the Beans and Corn
In a small skillet over medium heat, warm the black beans and corn with a splash of oil and the cumin for 2 to 3 minutes until heated through. Season with salt.
Reheat the Beef
In the same skillet over medium heat, warm the shredded beef with a splash of its braising liquid for 2 to 3 minutes until heated through and the edges begin to caramelize.
Assemble
Divide the cilantro-lime rice among four bowls. Add a generous scoop of beef to the center. Arrange the beans and corn alongside.
Top and Serve
Top each bowl with fresh pico de gallo, avocado slices, and sour
Notes
Add lime juice and cilantro to the rice off heat only - adding them to the cooking water mutes the flavor completely.
Store the hot components (rice, beef, beans) in separate airtight containers for up to 4 days. Add the cold toppings fresh at serving.